m^ j^'isfessamsaaiisiataiitaiiiMK v 



^ Drawing 

^^TRADE SCHOOtS 



C.C.LEEDS 








T^'ir- 



D.VAN NOSTRAND COMPANY 



PUBLISHERS 



NEW YORK 




Copyrightl^" 



COPYRIGHT DEPOStr 



The D. Van Nostrand Company 

intend this booK to be sold to the Public 
at the advertised price, and supply it to 
the Trade on terms which will not allow 
of dbcount. 



(TarneQlc ^ecbntcat Scboolg ^eyt l&oohe 



MECHANICAL DRAWING 

FOR 

TRADE 5CH00LS 

BY 

CHARLES C. LEEDS 

Assistant to Head of School for 
Apprentices and Journeymen . 
Carnegie Technical Schools 



MACHINERY TRADES EDITION 




NEW YORK 

D. VAN NOSTRAND COMPANY 

1909 



COPYRIGHT, 1909 

BV 

D. VAN NOSTRAND COMPANY 



.'b 



^''s 



VIA 



THE 

VAN NOSTRAND PRESS 

NEW YORK 



LIBRARY of CONGRESS 

Two Copies Received 

APR 14 \m 

Xopyrignt Entry 
CLa'sS a, XXt No, 



PREFACE 



This -^vork on ^Mechanical Drawing lias been prepared with the 
purpose in \'iew of thoroughly grounding young draftsmen, and others 
of the various machiner}- trades, in the pruiciples of Mechanical Drawing. 
It is also intended to familiarize them with modern drafting-room practice. 

The author's conviction that the tise of models serves to develop 
copyists and often tends to stunt or destroy a draftsman's creative 
faculties, has led him to discard entirely the use of models in teaching 
Mechanical Drawing, and he feels that it will be obvious, even to the 
casual observer, that when a student has been given a model of his 
subject for the drawing lesson, little or no effort will be required from 
his imagination. 

The model stands before his eyes, complete; no effort on his part 
is necessar}-. ^ATien the student, however, is given a blue-print or 
drawing of the subject, difficulties arise at ever}- step. In order to under- 
stand the meaning of the views shown, he has to study the subject care- 
fully and grasp the meaning of each line. In short, he has to think. 
To form a mextal picture of the piece illustrated is more difficult 
than mere copying; it is also more beneficial. 



That facuhy of imagining, that mental picturing so necessar\- to 
the good draftsman or designer, can be developed within ever\- stu- 
dent. It is a part of his development, just as an understanding of the 
meaning (either definite or conventional") of each line of a drawing 
is a part of his development. 

Convinced of this fact, the author has arranged these lessons in a 
manner which he believes will attract and hold the attention of the 
student. Each lesson will guide the student by easy steps, illustrate 
some fundamental point in Mechanical Drawing, and work as a whole 
towards the development of the creative draftsman. 

The results obtained by the author at the Carnegie Technical 
Schools, through this mode of teaching, justify him in this belief, and 
prompt him to place within reach of every one interested in the sub- 
ject this simple treatise, which he hopes will be as fruitful in the hands 
of others as it has been in his. 



Chaexes C. Leeds. 



March 15, 1909. 



LESSON No. I. 



PENCILS. — It is ven' important that the student of Mechanical 
Drawing should have good tools to work with, and just as important 
that he should learn to take good care of them that they may be ahvays 
ready for use. No tool is more used in mechanical drawing than a 
lead pencil, yet no tool is so greatly abused, mainly because it is not 
very expensive. 

Pencils for drawing are made of various degrees of hardness to suit 
the purposes for which they are to be used. There are a number of 
methods of designating the degree of hardness, — one of the commonest 
being to mark them 2H, 4H, 6H, etc., the harder the pencil, the higher 
the number preceding the H. 

For drawing on the common Manilla papers, 4H is a very satis- 
factory pencil, though 6H wears better and does not require to be 
sharpened so often. 

To do accurate drawing, it is necessary to keep the pencil well 
sharpened. The following methods for sharpening are highly desirable. 

ROUND POINT.— The first method is known as the "Round 
Point." This is produced by first cutting away the wood, as sho^^•n in 
the illustration, Fig. i, and then sharpening the lead on a file. 

Round not straight. 





Do this with your kn.fe. 



File the point. 



Fig. 1. 



About one inch from the end of the pencil, beginning on one of the 
six corners, cut away the wood in a clean manner so as to bare about 
f" of the lead; then sharpen it on the file by drawing it towards you. 
Turn the pencil slowly away from you, taking a fresh hold with each 
stroke, so as to keep the pencil turning on its axis as it is moved along 
the file. 




FLAT POINT.— The "Flat Point" is very useful when it is 
desired to draw very fine accurate lines, such as the center lines, con- 
struction lines, etc. In sharp- 



ening the flat point, enter the 
knife about one inch from the 
end of the pencil on one of the 
flat sides (not corner), and cut 
away the wood in the manner 
sho'^vn in the illustration. Fig. 2, 
baring about one-half inch of 
the lead. 

To sharpen the lead, slide it 




Fig. 2. 



back and forth along the file, forming a long chisel-like point. 

The flat side of the lead should parallel the flat side of the pencil 
when the point is finished. 

PAPER. — The drawing paper commonly used in commercial draft- 
ing rooms is known as Manilla paper. 

There are a great many difl'erent grades of this paper manufactured, 
but the main points necessar}- to keep in mind when making a selection 
are: color, erasing qualities, and toughness of fibre. 

The standard sizes of drawings 
adopted by the Carnegie Technical 
Schools are: A sheets 22"X3o", B 
sheets i5"X22", and C sheets ii"X 

IS"- 

Drawing paper should be fastened 
to the board as smoothly as possible; 
for it is very diflicult to make an accu- 
rate drawing on paper which does not 
lie flat on the board. 




Fig. 3. 



LESSON No. I.— Continued. 



The metliod of mounting paper, shown in the above illustration, 
Fig. 3, needs ven,' little explanation, and if the student follows the direc- 
tions with reasonable care, the result will be entirely satisfactor\'. 
Place the tacks in the order numbered, stretching the paper in the 
direction indicated by the arrows. 

Push the tacks well down, so that the heads bind the paper closely; 
this will also enable the T square to slip over them easily without 
knocking small chips out of the edge of the blade. 

DR.WVING BOARD. — T SQUARE. — TRIANGLES. — The 
Drawing Board should be made of a soft wood, well-seasoned white 



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Fig. 4. 



pine preferred, so that the thumb tacks may be easily pushed into or 
drawn from it. 

One end of the board must be perfectly straight, as well as smooth, 
and free from bumps or high spots. 

A T Square of well-seasoned pear wood is inexpensive and should 
give satisfactory resuUs. 

The inside edge of the head and the upper edge of the blade should 
be perfectly straight, and be smoothly and accurately finished. 



The Triangles commonly used by draftsmen are the 45° and the 
3o°-6o° angles; and it is preferable that they should be made of some 
transparent material. 

The student should realize the necessity of learning to use these 
tools properly if he desires to do accurate work. The head of the T 
Square should be kept pressed against the edge of the board when in 
use ; place the hand at A, Fig. 4, rather than at B, and press the blade 
flat against the board by placing the thumb at C. 

The student should work from the left side of the board at all times, 
and when drawing vertical lines, he should use the left side of the 
triangle as a ruling edge. 

The left side of the triangle is the most natural one to use, as the 



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Fig. 5. 



arm is held in an easy position when drawing a line away from the 
square blade. Besides, when tracing with ink, the student would find 
it extremely awkward and tiresome to use the right side of the triangle. 



LESSON No. I.— Continued. 



Hence this general statement: Accurate work is practically impos- 
sible when both sides of the triangle are used to rule vertical lines on 
the same drawing. The reason is that triangles are very often inaccu- 
rate. 

Fig. 4 shows where the trouble lies and gives the student a way of 
testing the accuracy of his own triangles. 

RULING LINES. — A very common cause of inaccurate work is 
the careless manner in which the lines of a drawing are ruled; if the 
student will consider the angle formed by the edge of the T Square 
and the surface of the paper as a groove, and then, leaning the pencil 
slightly away from the ruling edge, drag the point along this groove, 
he will have no difficulty in ruling a straight line. 

(a) in the illustration, Fig. 5, shows the correct method, and (6) the 
incorrect one. 

WEARING THE PENCIL POINT.— Draftsmen pick up a 
good many little tricks or habits that are of advantage in their work. 
One of them is a method of wearing the pencil point in such a way 
that it will stay sharp a long time. 

The Flat Point is shown in illustration (a). Fig. 6, and the method 
is too evident to need further explanation. 



A 



as shown at (6), preserve for a long time the sharp conical point of the 
pencil. 

SCALE. — The draftsman's flat rule (or scale, as it is generally 
termed), which is graduated in sixteenths on one edge and thirty- 
seconds on the other, will be found very satisfactory. 

\Vhen selecting a scale it is advisable to choose one with the grad- 
uations cut in a white surface, as the strain on the student's eyes is 
much less than when using a steel scale or one of plain boxwood. 

ACCURACY. — If we stop to analyze the mechanical part of the 
work of a draftsman, we realize that a great portion of his work con- 
sists in placing points on the surface of the paper and connecting them 
with lines, or in drawing lines through them. 

When enough of these points and lines have been placed upon the 
paper, the drawing of the figure is complete. 

To make a mechanical drawing accurately, it is absolutely essential 
that the points be placed in their proper positions. 

In connecting them with lines, or in drawing lines through them, 
the lines should pass through the center of the points. 

If the student is unable to do this properly, it naturally follows that 
he is unable to make an accurate drawing. 

LINE THROUGH A POINT.— ist. With the round-point end 
of the pencil, make twenty small points upon the paper, one above 



Fig. 6. 



When ruling a line with the round point, turn the pencil slowly and 
deliberately, so that it revolves on its axis as it is dragged along the 
ruling edge. 

This method will result in lines of an even thickness and color, and. 



Fig. 7. 

another, and about \ of an inch apart ; then, with the flat -point end of 
the pencil, rule with the T square a fine, clear, straight, horizontal line 
through each point, as shown in Fig. 7. 

These lines may be 6 or 8 inches long. Rule ten of them by adjust- 
ing the blade of the T square up to the point, and ten by placing the 



LESSON No. I.— Continued. 




Fig. 8 



LESSON No. I.— Continued. 



pencil point in position and bringing the ruling edge gently up to it. 
These fine lines are called "construction lines," from the fact that 
when used in practice, the drawing is built upon them. The student 
should endeavor to '•'split" the point each time. 

Now, with the roimd-point end of the pencil, "line in" about 3 
inches of each line to the right of the point. 

By the term "line in," we mean to make that portion of the line 
heavier, so that the result will be a strong, clear line, such as should be 
shown on a finished drawing. \Mien lining in, the student should be 
ver}' careful to cover the construction line perfectly. 

Lining in a little above or a little below the construction line results 
in inaccurate work. 

2d. Repeat above, ruling vertical lines and 45° lines, tising the T 
square and the 45° triangle. 

LAITXG OFF DIMEXSIOXS.— 3d. Draw fifteen straight lines 
just 4 inches long; these lines to be horizontal, vertical, and 45°. 

In each case use the method described above; first a fine construc- 
tion line more than 4 inches long, then, using the scale in the manner 
showTi in the illustration, Fig. 8, lay off two points which are exactly 
4 inches apart, and "line in" that part of the construction line between 
points. 

THREE-INCH SQUARE.— 4th. Using the T square and the 45° 
triangle, construct a 3-inch square. Rule the lines in the order shown 
by numbers in the illustration. Fig. 9. 



Lines i, 2, and 3 should be construction lines at first. 
Finish the square by lining in these sides. 



/ 

Fig. 9. 



^Mien the square is finished, the length of each side should be 
exactly 3 inches. 



LESSON No. 2. 



ACCURACY. — The student should at all times endeavor to make 
accurate drawings, and he will find that it is only by constant effort on 
his part that this can be accomplished. 

This lesson is a test in accuracy, and it is necessary that the student 
should exercise great care in laying out these figures. 

CO^ilPASS POINTS.— Get the pencil compasses ready for use. 

In preparing the large compass, remove the pencil leg and, with 
the file, produce a "flat point" very similar to the "flat point" of the 
pencil. Trim off the sides so as to get a narrow "flat pcint" as shown 
in the illustration, Fig. lo. 



The flat side of the lead should be set at right angles with the 
needle point. If this requirement is not met with, the compass tends 



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Fig. io. 

The pencil point of the spring-bow compass should be sharpened 
in the same manner, except that the finished point should be slightly 
narrower than the one in the large compass. 

SETTING LEAD.— ^\^^en adjusting the legs of the large com- 
pass, see that the pencil point is slightly shorter than the needle point; 
about to the shoulder of the latter. 




to open when it is turned in one direction, and to close when turned in 
the other. 



LESSON No. 2. — Continued. 



After the compass legs are properly adjusted for length, test the 
setting of the lead by drawmg a circle clockwise, then, without remov- 
ing the needle point from the paper, swing one counter-clockwise. 
The result should be one clear sharp circle; if this is not the case, the 
lead should be adjusted to correct the error. 

SETTING COMPASS.— With the large compass, take a radius 
of i^ inches and describe a 3-inch circle. 

Now, test the circle for a diameter of 3 inches, using the scale. 
Reset the compass and repeat above test several times, so as to gain 
confidence in setting the compass. When setting the latter, handle it, 
and also the scale, as shown in the illustration, Fig. 11. 




Fig. 13. 

TANGENT CIRCLES.— TRIANGLE.— Describe three 2-mch 
circles tangent to one another. 

Surround the circles by a tangent triangle. "Line in" the triangle 
and test it for accuracy, using the dividers; the sides should be of 
equal length. 



Repeat this three times. 

Great care should he exercised by the student in laying out this 
figure, which presents so many chances for error that it is quite diffi- 
cult to draw correctly. 

SQUARE. — Construct a 3-uich square, using the T square and 
triangle. The square to have roimded comers of i-inch radius, made 
with the bow-pencil compass. 

The finished square should be "lined in" so that there are no 
visible joints. 

\A'here rounded corners join straight lines on a mechanical draw- 
ing, the joint should be so nearly perfect as to be unnoticeable. Care 
in these little details adds great!}- to the attractiveness of a drawing, 
and they should never be overlooked. 




Fig. 13. 

The student should observe that in the illustration, Fig. 13, the 
square is first laid out in faint construction lines, then the comers are 
rounded, and, finally, the sides are "lined in." 

The roimded comer lines should be made as hea\y as it is desired 
to make the rest of the outline, so that in "lining in" the sides, the 
lines may be made of the same weight. 



LESSON No. 3. 



FLANGED PIN. — Make a full-size three-view outline drawing of 
the flanged pin shown in the illustration, Drawing C-iooo. 

Mew (a) shows the shank end of the pin as seen from the position 
of (a). View (b) is a side view of the flanged pin, and (c) is a view 
of the round end as seen from the position of view (c). The student 
should study the illustration carefully, and tr}' to understand clearly 
the meaning of each line. The position of each view is given in rela- 
tion to the edge of the sheet. 

THE DRAWING.— To make the drawing, first lay out the center 
lines, as they fix the positions of the views. Second, draw view (a), 
throwing in the circles, then, with the T square and 45° triangle, construct 
the square representing the shank end. Third, draw view {b), setting 
the compasses with care each time, so that the circles are drawn exactly 



to scale. Fourth, lay ofi" the lengthwise dimensions of the pin, then 
draw vertical construction lines through these points (lines of any 
length) ; nowplace the T square so as to project the horizontal lines of 
the pin from the end views. With a |-inch radius, throw in the curved 
lines representing the chamfer on the shank end. Observe how the 
radius center line is projected from the end view. 

FINISHED DRAWING.— In finishing the drawing, "line in" 
the whole outline with care to give it a neat appearance, and to make 
it clear and distinct, so that all the lines can be easily seen through the 
tracing cloth. Do not put in any of the dimensions. The finished 
drawing should show only the outlines of the pin with the vertical and 
horizontal center lines. 




Center Lines 



CLASS Industrial trade Machinist 

NAME John W. Roberts date Feb. 16- 06. 



THE CARNEGIE TECHNICAL SCHOOLS 

OT^SB^fSr^. PA. 

School or a=or£st'C£S A.•^o journzymen 

MECMASICAL DfAWIMG 



Flanged Pin 



SCALE full Size 



DW6.Ha. C./QOO 



LESSON No. 4. 



MACHINE BOLT.— Make a full-size three-view mechanical 
drawing of the i^-inch machine bolt shown in the illustration, Drawing 
C-iooi. Mew (a) represents the end of the bolt head as seen from 
the position of (a). View {b) is a side view of the bolt and hexagon 
nut. View (c) is an end view of the threaded end of the bolt and of 
the hexagon nut as seen from the position of (<:). The positions of 
the views are given in relation to the edges of the paper. 

THE DRAWING.— Lay off the center lines first, so that the 
positions of the views are fixed at the beginning; do not let them 
"happen" as regards location. 

In drawing view (a), lay out the 2i-inch construction circle, and 
then with the T square and 45° triangle, draw in the outline of the head. 

View (f) is drawn in the same manner, that is, first the af-inch 
construction circle, then, using the T square and the 3o°-6o° triangle 
draw the outline of the hexagon nut, and finally throw in the ij-inch 
circle to represent the end of the bolt. 

Having c'rawn views (a) and (c), now lay off the lengthwise dimen- 
sions of view {b), and draw vertical construction lines through these 
points (lines any length). With the T square, project the horizontal lines 
of the bolt from the end views, these lines to be light construction lines, 
until their true length is known. Now swing in the various radii, 
make them as heavy as the final outline is to be, and line in the bolt 



and nut completeh', so that the whole outline stands out clearly and 
distinctly. 

SCREW THREADS.— The threaded end of the bolt is indicated 
by alternate light and heavy lines, the heavy lines being shorter than 
the light ones. This is a conventional method of indicating screw 
threads, and it has the merit of being easily understood and is inex- 
pensive. 

Wiile it is not essential that the space between the light lines should 
be just the same as the pitch of the thread, or that the lines should be 
sloped at exactly the correct angle, it is of considerable importance 
that the threaded surface as a whole should look approximately 
correct. 

When the slope is correct for a single-thread screw, a line drawn at 
right angles to the center line of the screw should touch the end of one 
of the thread lines at one side and pass midway between that line and 
the next at the opposite side, as indicated by the light dash line d-e. 
In other words, the slope equals half of the pitch of the thread. 

Place the dimensions just as shown in the illustration, and make 
the figures carefully, so that there can be no doubt as to their meaning. 
The dimensions which refer to the position of the different \-iews 
should be left off, as they were intended to aid the student in locating 
the views, and have no other value. 




?p- 



6 Thds. per inch 





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Ci/4Ss Industrial trade Machin'isf 
NAMC John W. Roberts datl Feb. 20^06. 



THE CARNEGIE TECHNICAL SCHOOLS 

PITTSBURGH, PA. 

School or App/penvces and Journeymen 

MECHANICAL OPAWING 



Machine Bolt 



SCALE ruil Size 



ona.No. C.I 001 



LESSON No. 5- 



LETTERING. — The average student does not fully appreciate 
the value of being able to letter well, and while he is seldom 
pleased with his lettering, he usually does not like to devote 
the necessar}- time to practice. A great many young draftsmen 
reach the point where they are able to make a neat, workmanlike 
drawing, the appearance of which they will spoil when they letter 
and dimension it. 

In making a study of the types of letters illustrated, take especial 
notice of the oval, which is the basis of most of the lower-case letters, 
and observe the proportions of this type; note also the slope of both 
t\-pes. 

The capitals are used mainly for titles and headings, while the 
lower-case letters are used for all notes shown on drawings and for all 
other purposes, except for titles and headings. 

As an aid in learning to letter, it is well to use guide lines as shown 



in the illustration. The student will find the slope guide lines a great 
help also in making letters of uniform appearance. 

FIGURES. — "What has been written in regard to lettering applies 
equally well to figures. 

It is of great importance that the student should learn to make his 
figures so well that no one should have anv trouble in reading them 
easily and quickly. Mistakes in the shops are very frequently caused 
by poorly written figures on drawings, and these mistakes are often 
very costly. The value of using great care at all times in placing the 
dimensions on drawings is thus clearly shown. 

THE LESSON.— Make a neat pencil copy of the illustration, 
using care with both letters and figures; note carefully the proportions 
of both. Leave off figures showing spacing of guide lines, as these 
were intended merely as an aid to the student in laying out his lesson 
sheet. 




CLASS Indusfrial trade NIachinisf 
NAME John W. Roberta date Nov. 12, 06 



THE CARNEGIE TECHNICAL SCHOOLS 

PITTSaUKGH, PA. 

School of AppREsnces ano Journeymen 

KIE'CMANICAL DftAWINQ 



Lettering - Figures 



SCALE Full Siza ■ dwg.no. C- 1002 



LESSON No. 6. 



SKETCHING. — ^^^^atever course in mechanical drawing the stu- 
dent may pursue, he will sooner or later desire to know something about 
sketching, or, at least, he will feel the need of it. 

A knowledge of sketching is exceedingly useful to men of most of 
the trades, and the lessons on this subject have been planned with the 
belief that they may assist the students to use their pencils more freely 
and easily in making simple mechanical drawings free-hand. 

METHOD.— The method that we shall follow, we shall call the 
"Short -stroke Method," from the fact that as we draw a line in any 
direction, it is not made by a single stroke of the pencil, but by a series 
of short strokes. There should be the smallest possible opening be- 
tween the ends of these short lines, and it would be better still if the 
ends were to just touch without overlapping. 

The object of using these short strokes is to enable the student to 
correct an error in direction at any point along the line. The result is 
that the general direction of the line is straight, and though there may 
be slight errors along the line, they in nowise cause any doubt as to 
its meaning. 

PENCILS. — For sketching, a pencil equalling an H or HB in hard- 
ness will give very satisfactor}' results, though a 2H Koh-i-noor will 
last much better. The latter, however, is just a little too hard except 
when used on Manilla paper. 

Learn to hold the pencil easily and naturally between the first and 
second fingers and the thumb, in a manner very similar to that used in 



Do not turn the paper to suit the direction in which a line is to be 
drawn, but fasten it down to the drawing board and try to develop that 
freedom of movement of fingers, wrist, and arm which will enable one 
to draw a line in any direction with equal ease. 

In drawing straight lines as indicated on the illustration, the student 
will soon discover that they are made in certain directions by a move- 
ment of the wrist mainly. In other directions it is mostly a movement 
of the fingers which gives the best results. 

It is quite difficult to make neat circles free-hand, but by putting 
into practice the following suggestions, the student should obtain satis- 
factory results. 

The student should sit upright while drawing, so that he may the 
better get a clear view of his work as a whole. By having the head 
well up over the work, the eyes can direct the movements of the pencil 
better, and they are in a better position to see if the desired shape is 
growing under the pencil, than if held close to the work. Start at a 
point on the left side, as indicated by the arrows, and with short strokes 
form the upper half of the circle. Then, starting at the same point, 
form the lower half in the same manner. 

THE LESSON.:— Fasten the drawing paper smoothly to the 
board and divide it into sections, as shown in the illustration. 

The straight lines should be drawn about J inch apart and in the 
directions indicated by the arrows. 

Draw the circles to the sizes shown, without using a rule; try to 
see how nearly correct you can make them by the eye. 




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CLASS Industrial trade Machinist 

NAME John W. Roberts date Mar. SO- 0$. 



THE CAR'NEGIE TECHNICAL SCHOOLS 

PITTSBURGH, PA. 

School of APPHEimccs and JotiRNcrMEN 

MECHANICAL DRAWING 



Sketching 



SCALE Full Size 



owe. No. C. 1002 



LESSON No. 7. 



PROPORTIONS. — It is a very valuable acquirement, when 
sketching, to be able to make the details of a drawing of the proper 
proportions in relation to each other. 

The scale of a sketch is of little importance, provided it is large 
enough to show clearly the piece or pieces we desire to illustrate. But 
that which is of importance is that each piece, or detail of the piece, 
should be drawn to the same scale. 

To obtain this result it is quite necessary that the student should 
train his faculty of obsers-ation so as to have a sense of measurement, 



and so that, without the aid of a rule, he may be able to draw a sketch 
approximately to a given size. 

The student will be helped to develop this facuhy if, in sketching, 
he practises drawing to a certain scale or to given dimensions. 

LESSON. — Make a neat free-hand full-size drawing of the figures 
shown in the illustration. Draw each figure to the dimensions given, 
as nearly as possible, without using a rule. 

Observe that two views are shown of each piece, and try to see 
the relation between the views. 






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ci/tss Indusfrial t/?ad£: Machinist 

NAME John W. Roberts datc: Mar. £0.06. 



THE CARNEGIE TECHNICAL SCHOOLS 

Pittsburgh, pa. 
School op apppc/^tic£s ano JouPucyMZN 

I'ECi-lANICAL Df^AWING 



Sketching 



scALC Full Size 



one. NO. C~I004 



LESSON No. 8. 



METHOD OF HOLDING PEN.— In learning to trace, one of 
the first problems which confronts the student is how to hold the 
instruments. 

In general, the ruling pen and the pen point of the compass should 
be held in such a manner as to bring the points of both jaws on the 
paper at the sam.e time, as shown at (b) of the illustration, Fig. 14. 




B 



M 



a 



Fig. 14. 



Do not lean the pen either toward the ruling edge or away from it, but 
hold it in a vertical plane, thus obtaining clean even lines free from a 
ragged edge. 

While the pen should not be leaned toward or away from the ruling 
edge, it will be found that the ink will flow more freely if the pen is 
leaned slightly in the direction in wJiicli Ihe line is being ruled, as shown 
at ((i). 



When using the pen compass for large circles, the legs may be bent 
at the joints, so as to meet these conditions. 

TRACING CLOTH.— The student will fmd one side of the trac- 
ing cloth with a glazed or calendered surface, while the other side has 
a dull finish. If the glossy side is used, it will be necessary to dust the 
surface with powdered chalk or talcum powder, as the ink will not flow 
freely otherwise. In a great many drafting rooms the dull side of the 
cloth is used from preference, as it takes ink very well without powder 
of any kind, though the powder makes the ink flow more freely. 



®i 





o)E 




/sf. Circles and Radii 



@E—- 



Snd. Horizontal lines 



3rd. Vertical lines 





E 




4-th. Angular lines 



Fig. is. 



CARE OF PENS. — A common mistake of most beginners is to 
fill the pen with too much ink, with the result that, before they realize 
it, there is a big blot on their work. This is not necessarily caused by 
the pen being filled too full, but it is frequently the cause. It is better 
to fill the pen oftener and to use less ink at one time. 

Another very good habit to acquire is to wipe out the pen each 



LESSON No. 8.— Continued. 



time fresh ink is to be put in, as the ink flows more freely from a clean 
pen than from a dirty one. 

TIL\CIXG FL.\XGED FIX.— Make a tracing of the pencil 
drawing of the flanged pin. 

WTien beginning a tracing, tack the cloth do^Ti carefully over the 
.pencil drawing, then set the compass pen to the desired width of line 
bv testing on the edge of the sheet, and, after it is properly adjusted, 



throw in all the circles and radii. Then, beginning at the top, rule in 
the horizontal outlines; next, beginning at the left side, rule in the 
vertical outlines and finally the angular lines. 

In ruling horizontal lines, use the T square as a ruling edge. For 
vertical lines, use the left side of the triangle, which should be held 
against the T-square blade. 

Do not use the scale as a ruling edge. 



LESSON No. 9. 



TRACING :MACHINE BOLT.— As mentioned in Lesson No. 8, 
begin bv adjusting the compass pen to the width of line desired for an 
outline. In deciding on the width of line, the student should bear in 





o 



y- 




/sf. Circles and Radii 



drc/. Vertical lines 





2nd. Horizontal lines 

Dimension tines 



4^fh. Angular lines 

Projection lines 




e^r^d pt 



5fh. Projection and Dimension lines^ 

Dimensions— Notes 
Fig. 1 6. 

mind that to get blue-prints with clear white lines, it is necessary 
the lines of the tracing be fairly hea\y; not the tine, "pretty" 
that beginners are so prone to use. 



that 
lines 



The illustration shows the various steps in making a tracing: First, 
throw in all the circles and radii; then, beginning at the top, rule in all 
the horizontal outlines; ne.xt, starting at the left side, rule in all the 
vertical outlines; and, finally, rule in the angular outlines. 

Now, adjusting the pen to a much finer line, rule in the projection 
lines; these lines for drawings of small figures should be composed of 
dashes i to f inch long, and for large figures ^ to f inch long. Do not 
let the projection lines touch the figure, but leave a slight opening 
between the end of the line and the figure. 

Next, rule in the dimension lines ; these lines for drawings of small 
figures should be solid except for the opening left for the dimension, 
but on drawings of large figures they may be broken lines of long 
dashes, — the length to suit the size of the drawing. 

Now, place the arrow heads on the dimension lines and put in the 
dimensions, using care to make the figures clearly. 

FINISHED DRA^^^NG.— In the finished drawing there should 
be a marked contrast between the weight of the outlines of the figure, 
and of the center, projection, and dimension lines ; the latter should be 
decidedly lighter than the outlines, ^^'hen these various lines are 
drawn to the proper proportions and are well arranged, the figure 
seems to stand out by itself and is much more easily imder- 
stood. 

ANTien the drawing is completed, print the title on neatly and care- 
fullv, as the looks of a good drawing will be spoiled if the printing is 
done in a careless, slipshod manner. 

Use a GiUott's No. 303 pen point for lettering and dimensioning 
the drawins 



LESSON No. lo. 



HIDDEN SURFACES.— Until the present time we have been 
using lines which could be seen on the surface, or which represented 
the surface of the figures that we have used as subjects for our draw- 
ing lessons. 

In mechanical drawing it is constantly necessary to show by some 
means, surfaces or details of parts that are hidden from view behind 
the surface shown by solid lines. 

Unless these surfaces could be indicated by some simple method, 
it would often be necessary to make additional drawings or, at least, 
additional views to show clearly the shape of the figure illustrated. 

The method commonly used to indicate these hidden surfaces is to 
draw them in, in the proper position, but to use dotted lines for this 
purpose. These dotted lines, or "hidden lines," as they are generally 
called, have a distinctly different appearance from the solid outlines of 



the rest of the drawing, and their meaning should be readily under- 
stood. 

THE LESSON. — These hidden lines are the essential feature in 
the present lesson. As they are constantly used in mechanical draw- 
ing, we wish to call the student's attention to them. 

Make a neat free-hand sketch of the clamp shown on Drawing 
C-1005. 

Finish your sketch neatly, copy carefully all dimensions, and be 
sure to place your name, the drawing number, and the title of the 
piece upon it. 

From )'our sketch make a full-size pencil drawing of the clamp; 
finish it completely with all dimensions, the title, etc. 

Use the "Short -stroke Method" in making your sketch. 



//H- 






^i 



H 




-^/j 



Jl. 



-|^i- 



■:t 



:i^ 






Ct/iss Industrial traoc Machinist 
NAME John VJ. Roberts date Oct. 6- O 6. 



THE CARNEGIE TECHNICAL SCHOOLS 

P/TTSBURGH, PA. 

School or Apprentices and journeymen 

MCCHANICAL DRAWING 



Clamp 



SCALE Full Size ona.No. C-1005 



LESSON No. II. 



SECTIONING. — When making drawings it is often necessary to 
show at least one view of the piece or pieces illustrated, with part cut 
away, or " in section," as it is generally termed. 

The advantage of this method is that it helps to show the shape of 
the piece more clearly, and often tlie dimensions can be placed to bet- 
ter advantage on a sectional view. 

As an aid in indicating that a piece is in section, the surface is cov- 
ered with lines called "section lines." These lines are drawn with the 
aid of a 45° triangle as a ruling edge, the triangle being held against 
the T-square blade and moved for each line. 

In this course of lessons we will use the section lines shown on 
Drawing C-1006 for all inetah, the only variation being that the lines 



should be spaced close together for small pieces and farther apart for 
large ones. 

WTiere two or more pieces assembled together are shown in section, 
the different parts are shown more clearly by sloping the section lines 
in opposite directions where the parts join. 

THE LESSON. — The important point in this lesson is the method 
of showing a piece in section. 

Make a neat free-hand sketch of the sleeve shown on Drawing 
C-1006; copy carefully all dimensions, and all necessary data. 

From your sketch make a full-size pencil drawing of the sleeve. 
Try hard for accuracy. 





CLASS Indusirial tradc tvlachinisi 

t4AME John W Roberts date Oci 24-06. 



THE CARNEGIE TECHNICAL SCHOOLS 

PITTSBURGH, PA. 
SCI-IOOL OF APPf/ENTICeS AMD JOURNEYMEU 
MECHAhUCAL DP AWING 



Sleeve 



SCALE Full Size 



DIV3.NO.C.I006 



LESSON No. 12. 



PROJECTION. — Mechanical drawings to be clearly understood 
and easily read should be made after certain fixed rules as to the 
arrangement of views in relation to each other. 

There are usually several correct arrangements for the different 
views of a body, but in each of them the same relationship between the 




Projection lines 



Plane 



Fig. 



views is maintained. To fully grasp the meaning of this, a knowledge 
of projection is necessary. 

Every student of Mechanical Drawing should make a study of the 
subject of projection, as a thorough knowledge of this subject is neces- 
sary in order to read drawings intelligently, and it is absolutely essen- 
tial for one who wishes to become a good draftsman. 

The definition of the word projection (as applied to Mechanical 
Drawing), given in the Universal Dictionary of Mechanical Drawing 



by Prof. Geo. H. Follows, is: "To throw forward in parallel rays or 
straight lines." "Projection means either the act or the resuh of pro- 
jecting parallel rays from the surface of a body, and of cutting these 
rays with a plane, so as to obtain on the plane a shape, corresponding 



Plane A 



Top view 




Plane B 



Projec'h'on lines 



Fig. 1 8. 



In Mechanical Drawing these 



point for point with that of the body 
rays are called projection lines." 

Fig. 17 is an illustration of a V block shown in perspective, the 
end view of the block being projected upon the plane. Projection 
lines are thrown out from the points or corners of the body, and the 



LESSON No. 12. — Continued. 



main points where the plane intersects these lines are those which are 
used in developing the outline of this body. 

This perspective is used simply to Olustrate the principle of pro- 
jection, while the illustration shown lq Fig. i8 is an example of a 
mechanical projection of the same block, showing the three views in 
the same plane. 

Theoretically, we start with the assumption that the body is located 
directly imder the top plane, and that the top view is projected up to 
this plane. The end view is projected upon plane A, and this plane is 
then s\\img up parallel with the plane of the top view. The same 
process follows for the side view; it is projected upon plane B, which 
is swung up parallel with the other two views, all of the ^-iews now 
being in the same plane. In actual practice, the draftsman would lay 
out the different views in the same relation to each other, but he would 
simply construct the ^-iews by means of his T square, triangles, and 
scale. 

As an aid to remember true projection, and in order to enable the 
student to ascertain the correctness of his projection drawings regard- 
less of the manner in which the views may be arranged, the following 
method is recommended. 

Observe if the different \"iews bear the same relation to each other 
as those shown in Fig. i8; that is, that, from the position of the end 



\"iew, looking toward the top view, one will see what has been drawn 
for the end ^•iew, and from the position of the side view, looking 
toward the top view, one will see what has been drawn for the side 
view. Furthermore, from the position of the top \"iew, looking toward 
the end view and side view, one can see what has been drawn for the 
top view. 

THE LESSON. — A number of pieces of various shapes are shown 
on Drawing C-1007, some of the views of each piece being incomplete. 
The student is expected to lay out a full-size pencil copy of this draw- 
ing, with all of the views properly completed. 

To finish these correctly it wiU be necessar}- for the student to keep 
in mind what has been written above in regard to pro^-ing that the 
views are properly projeaed. 

Do this work neatly, showing aU necessar}- hidden lines, but remem- 
ber that the important point is to show a clear understanding of simple 
projection. 

Place all dimensions as shown, and print the title on neatly. Qual- 
ity, not speed, counts at present in all this work. 

In Fig. I, view C is complete; finish A and B. 

In Fig. 2, \-iew B is complete; finish A and C. 

In Fig. 3, view C is complete: finish A and B. 

In Fig. 4, view C is complete; fimish A and B. 




Fig. I 





A 






j" ) 




i 


C^' 




1 




T 



/v^. 5 



Planes 




Fig. 2 





— /i— 


— • 


/• 


•> /" — • 


/ 


— 


c 


— 


'■^^t 




+ 





<^i 



B 



Fig 4 




r i-^i«o 

^- n 



_■§ J3"lT 



■^<^-. "= 



ct^ss Industrial tradc /Machinist 

NAME John W. Roberfs date Sept 25. OZ 



THE CARNEGIE TECHNICAL SCHOOLS 

PITTSBUnsH, PA. 

School of Apppehticcs and Journeymen 
mechanical drawing 



Problems in Projection 



5CALE Full Size 



dwq.no. CJ007 



LESSON No. 13. 



FLANGED PULLEY.— The figures on Drawing C-1008 repre- 
sent a side view and a true sectional view of a Flanged Pulley. 

The conventional method of indicating screw threads is used in the 
holes for the set screws ; note that the threads appear to be left hand. 
These threads are in reality right hand, and it is desired that the stu- 
dent shall reason out for himself just why it is correct to show the 
threads in this manner. 

This lesson is intended to give the student a clearer conception of 
the subject of sectioning; to help him to make a mental picture of 



what the pulley looks like when cut in half along the vertical center 
line. Make a free-hand sketch of the pulley, copying carefully all 
dimensions and necessary information. From this sketch make a 
full-size pencil drawing of the pulley, placing all dimensions just as 
shown on the illustration. 

When dimensioning a drawing, bear in mind that your drawing is 
to be used as an instrument to furnish exact information to some one 
in the shop, and unless you do your work carefully and accurately, 
costly mistakes may be the result. 





Drill ^Wap^ -20 Thd. 
for^'xfHdlss. Set- Sc. 



CLASS Industrial retAOE Machinist 
NA.ME Jofin l^. Roberts date Oct. 16- 06. 



\THE CARNEGIE TECHNICAL SCHOOLS 

PITTSBURGH, PA. 
School or Apprentices Afsio JouRNEYMerj 

MECHANICAL DRAtvING 



Flanged Pulley 

SCALE Full Size D^G.No.C-IOOS 



LESSON No. 14. 



HAND ^^'HEEL. — In our previous lessons on sectioning we have 
dealt with true sections, while, in the present lesson, the sectional view 
shown of the Hand WTieel is what is called a "conventional section." 
In other words, it is not a true section, but a special one which is 
used because it illustrates the shape of the piece more clearly for 
the pattern maker and machinist. The draftsman can lay it out 
more easily and quickly as well — an economy that should be con- 
sidered. 

As an illustration of the convenience of special sections, note the 
conventional section of the arm of the hand wheel; without this section 
it would be pretty hard to give the pattern maker a clear idea as to the 
shape of the arm. 

This conventional method of sectioning is used constantly on draw- 
ings of such pieces as wheels, pulleys, and gears with arms. 



LESSOK.— Make a full-size pencil drawing of the Hand Wheel. 

Place all dimensions just as shown, with the exception of those that 
refer to the handle; these dimensions should be left off, as they were 
intended merely as an aid to the student. Mark this part "No. 2 
Handle." When the pencil drawing is complete, make a tracing of it. 
Try to do this work neatly; make the lines of the tracing clear and dis- 
tinct, keeping in mind the instructions given in Lesson No. 9. 

When drawing the ball of the handle, do not try to make the two 
radii (i^ and i inch) touch, as they should be joined with a straight 
line. The student should bear in mind that where radii swinging in 
opposite directions are to be joined, that a straight line should be used 
for this purpose, otherwise the line appears to have a corner or uneven 
place. Where the radii are small, as at the stem of the handle, the 
rule may be overlooked. 





CLASS Industr'iaf .trade Mochinisf 
NAME Uohn \/V. Roberts. date 



THE CARNEGIE TECHNICAL SCHOOLS 
pittsburgh, pa. 

School of Apprentices and Journeymem 
mechanical drawing 



8 Hand Whetbl 

SCALE F'ull Size DWG. (vo. C-/009 



LESSON No. 15, 



DRAWING TO SCALE.— In all of our previous lessons, the 
pieces illustrated have been drawn full size; in our present lesson we 
shall take up the subject of drawing objects smaller than full size, or 
"drawing to scale," as it is generally termed. 

In most modern commercial drafting rooms, the drawings are made 
on paper of certain sizes. These standard sizes (usually three or four) 
are adopted to suit the needs of the manufacturer, and each of the 
machine parts bulk is shown on one of these standard-size sheets. 

Small parts may be drawn full size, but large ones must, of necessity, 
be drawn to a smaller scale, as ^ size, I size, and i size. 

These are the scales usually adopted by manufacturers of machinery. 
The piece is drawn to the scale necessarv' for clearness and best suited 
to one of the standard-size sheets, while the dimensions are placed in 
the same manner as if the piece were drawn full size. In other Avords, 
the dimensions must show the sizes to which the piece is to be finished 
in the shop. 

In drawing to a given scale, that scale becomes our unit of measure- 
ment. As an illustration, take our present lesson, in which the student 
is expected to make a half-size drawing of the Lathe Face Plate. 

As i inch is our unit of measurement, ^ inch equals i inch, but 
instead of dividing each dimension by two, read it thus: "if halves 
for if inches, 5 halves for 5 inches, f halves for f inch, etc." 

If the student will carefully study the illustration in Fig. 19, he 
will observe that the divisions can be made on the scale by simply 
training the eye to perform this operation. 

As an aid in readily locating a dimension on the scale, look for the 
nearest large graduation ; the full-size dimension on Fig. 19 is sff inches, 
a thirty-second less than sf inches, Avhich figure can be found at once. 
To find 5II inches half size, look for sf inches half size and point back 
toward zero one-half of the space between graduations. To locate 
5II inches quarter size, look for sf inches quarter size and point back 
toward zero one-fourth of the space between graduations, sff inches 
one-eighth size is located in the same manner. 



B)' this method it is necessary for the student to keep but one 
dimension in mind when making a division, and when he learns to 
read his scale properly, he is much less liable to make mistakes than if 
he were to make his divisions in the usual way. 



ru// Size 



J. II 



5j? ones 



sSi halves 



£ " '^ 5§2 quarters^ 

\5M eighths I 

8 



iTfnfiTfiTi^^ 



Fig. 19. 

To get a radius for half-size circles, set the compasses to the dimen- 
sion quarter size. For example, to draw the end view of the hub 4-inch 
diameter half size, take a radius of 4 quarters. 

LESSON. — From the illustration, make a half-size pencil drawing 
of the Lathe Face Plate. 

Section AB is cut along the line AB, and is a conventional method 
of showing a true section along this line. 

Section CD is necessary to give the pattern maker a clear idea of 
the shape of the metal back of the T slot. 

\\Tiere dimensions are given in decimals, draw that part to the near- 
est sixty-fourth. 

Study the illustration carefully, so as to get a clear idea of the mean- 
ing of each line. Do not simply copy; try to make a mental picture of 
the shape of the piece. 

Use the edge of your scale, which is graduated in sixteenths, and 
work from dimensions given. 




Section C-D 



Bore P.034 
Tap 2£- 6 Thd. 

a s. std. 




Section A-B 



CLASS Industrial trao£ Machinlsl 

NA»e John W. Roberis date 0ci20-06. 



THE CARNEGIE TECHNICAL SCHOOLS 

pittsburgh, pa. 
School of Apprentices and Journeymen 
mechanical drawihg 



Lathe Face Plate 

SCALE p S'ze DiVC.Na. C^IOIO 



LESSON No. i6. 



ASSEMBLY DRAAVINGS.— It is common practice in most 
draflinii rooms to make drawings whicli sliow several details of a 
macb.inc fastened togetlier. Tliese drawings are called "assembly 
drawings," and they are of great value to tlie men in the shop who 
erect or assemble the machines. They are very necessary also Avhen 
ordering the "stock" or materials from which to build the machines, as 
the "Bill of Material" contains all the necessary information for this 
purpose. 

The illustration is of a "Positive Clutch Coupling," so called from 
the fact that the motion transmitted by this coupling is positive, there 
being no chance for one-half to slip or slide over the other, as in a 
coupling where one-half turns the other Ijy means of friction. 

The stationarv half is keyed tight to the shaft on which it is mounted. 
The sliding half, which is on a separate shaft, is fitted in such a manner 
as to slide freely lengthwise on the shaft, while revolving with it. 

These shafts are held in line by bearings, one shaft being the 



"driver," the other the "driven." WTien the sliding half of the coup- 
ling is moved over until the ends of the halves lock together, the two 
shafts revolve as one. 

The end view of the stationary half shows clearly the shape of the 
lugs for interlocking. 

Note the method of indicating a break in the shaft; this method is 
alwa)s employed to indicate a break in a round piece of metal. 

LESSON. — Make a half-size drawing of the coupling. 

The sizes of keys may be obtained from the "Bill of Material." 

WHien laying out the "Bill of Material," use great care with letters 
and figures, as this information must be accurate and should be clearly 
shown. 

When the pencil drawing is finished, maue a tracing of it; the lines 
of the tracing should be fairly heavy, so that blue-prints made from it 
will show the figure with perfect clearness. 





Sliding fit 



Bill or Material- 



Item 
No. 


Description and Material 


Pat No. 


Req. 




Q) 


Stationary Clutch C.I. 


A 20I 


/ 


• 





Sliding Clutch C.I. 


ft 


1 




(D 


fxfe "■54 reather Key C.R. 




1 




@ 


|"x|'xJ4" Key C.R. 




1 




< 9". 


o5' _ 


7" . 


9' , 






^ 8 


/6 






'*4 









CLASS Inp/ustrial traoc ' f^achinist 

HAME John V\l. Roberts date Oct. 26. 06. 



THE CARNEGIE TECHNICAL SCHOOLS 

PITTSBURGH, PA. 

School of Appf^rNT/c£S and Journeymen 

MLCHAfJICAL OKAWINQ 



Positive Clutch Coupling 



LC p S/ze 



SCALC 2 

I 



owe. NO. C-l oil 



LESSON No. 17. 



COUPLING. — The assembly drawing used for the present lesson 
is of a "Compression Shaft Coupling." 

This coupling can be clamped around the ends of two shafts, the 

Across 




R=Bolt d'la 



r'= I^XBolfdia. 



Fig. 20, 



two halves of the coupling being held together by means of the bolts 
shown. The upper half of the coupling is fitted with a key which 
keeps the shafts in line. 

On assembly drawings it is not customarj' to give the dimensions of 



pins, screws, bolts, and similar details. The sizes only of these small 
parts are given, so that they can be ordered from the storeroom, where 
they are kept in stock. 

Most modern drafting rooms are supplied with "Data Books" or 
sheets of stock sizes, from which the draftsmen obtain all necessary 
dimensions of these small details. 

No dimensions are given for the bolts shown in the present lesson, 
but the student may obtain the size of bolt and nut from the "Bill of 
Material." 

From the following data the student is expected to calculate for 
himself all dimensions necessary to draw bolts and nuts to the correct 
size. 

If in doubt as to meaning of terms given beloAV, refer to illustration, 
Fig. 20. 

SIZES OF NUTS AND BOLT HEADS. 

Sq. nuts or bolt heads across flats = ijxbolt dia. + | inch. 
" " " " " " corners=dia. across flats X1.414. 
Hex. " " " " " flats = iJX bolt dia. + i inch. 

" " " " " " corners =dia. across flats X 1. 1 56. 
Height or thickness of nuts = bolt diameter. 

" " " " bolt heads = bolt diameter X. 80. 
"Length of Bolt" always refers to length under the head. Notice 
Drawing C-iooi, Lesson No. 4. 

Make a half -size pencil drawing of the coupling. Drawing C-1012. 
Remember that accuracy and neatness are points of great import- 
ance. 

Make a tracing of the finished pencil drawing. 



Ream fit 







Sec f ion A-B 



^/T 



-10 
A 



-H- 



-^K 
T* 



,7' 



€^ 



-1^ 



BfLL OF Material 



Item 
No. 


Oescn'pf/'on and Material 


Pat No. 


Req. 


(/) 


Half Coupling C. 1. 


A.200 


1 


® 


»» 99 ft 


ji 


1 


® 


i'xBfM.B. Tap Bolt nith Nut 




6 


@ 


l\^^xlO'HeY 




1 




CLASS Indusfrial trade t^actiinlsf 

HA»E John W. Roberts oatc Oct. 20-O6. 



THE CARNEGIE TECHNICAL SCHOOLS 

PITTSBUfGH, PA. 

School of Adprentices and Journeymen 

mechanical drawing 



Cot^PRsssioN Shaft Coupling 



7 o- 

SCALE 2 oize 



DWG NO. C-/0/2 



LESSON No. i8. 



PROJECTION. — Two problems in projection are shiown on Draw- 
ing C-1013. 

(a). Fig. I, is an end view of a block with all dimensions shown. 
(b) is a partly finished front view, showing the length of the block. 

View (a) is projected upon a plane which is set at an angle of 45°; 
this plane is then raised to a vertical position and swung around one- 
fourth turn or 90°, so as to show the front view (b). 

\'iew ((•) should be an end view of the block tilted at an angle of 45°. 

Lay out the three views full size, finishing them completely and 
placing them in the positions indicated on the drawing. 

Fig. 2 is a side view of a frustum of a hexagonal pyramid with the 
base cut away at an angle of 30°. 



The small end or top of frustum is ij inches across fiats, and the 
large end 2 inches across flats before cutting off a portion of the base, 
as shown by the dotted line. 

The student is expected to lay out the three views of this piece, the 
top and edge views to be placed in the positions indicated on the draw- 
ing. 

Remember that this lesson is intended purely as a study in pro- 
jection, and do this work very carefully. 

If the student fully grasps the principles of projection, he will have 
mastered one of the most difficult and most important portions of the 
subject of mechanical drawing. 

It is not necessary to dimension the pencil drawing. 



P/ona 




Project end vien here, 
c 



Fig.2 



Edge viev/ here 



CLASS Indusfria/ jraoc Machinist 

MAMC John i^ Roberts date Oct /O-OT^ 



THE CARNEGIE TECHNICAL SCHOOLS 

pittsburgh, pa. 
School of apprentices and Journeymen 
mechanical drawing 



PROBLEt^s IN Projection 



SCALE Full Size DWG No. 0-1013 



LESSON No. 19. 



COUPLING. — From the sketch shown on Drawing C-1C14, make 
an accurate haU"-size pencil drawing and tracing of the Safety Flange 
Coupling. 

This coupling derives its name from the flanges that extend out 
o\cr the bolt heads and nuts, keeping the workman's clothing from 
ijcing caught, thus preventing many serious accidents. 

Note that the shafts are of diflerent diameters and that each half 
coupling is fitted with a taper ke\-. These keys are tapered on one 
side only — that which is set in the hub of the coupling. When assem- 
bling, the half coupling is forced onto the shaft and the keys are fitted 
before the two halves are bolted together; this brings the large end of 
the ke}- at the end of the shaft, so that when the halves are fastened 
together, the kevs cannot work loose. 



Observe that one-half of the coupling is made with a recess 3! inches 
diameter by ^ inch deep, to receive the boss on the other half 
coupling; this is for the purpose of keeping the halves in line with 
each other. 

The student is expected to plan the "Bill of Material" required for 
this drawing. Remember that it is quite necessary to show the size, 
material, and quantity of each item needed for one complete coupling. 
When items are not exactly alike (as the taper keys), they must be 
given separate item numbers. The shafts should not be considered as 
items. 

Remember that dean, accurate work counts most, not work that is 
rushed out in a haphazard fashion. The lettering and dimensioning 
must be carefullv done. 



Driving fit 



Finish all over 



-^8 



<- 7' J, /j'.l, ,Si '_ 




CLASS Industrial trade t/lachlnist 

NAME Jotin W.RotJcrts date Nov. 1 6-06. 



THE CARNEGIE TECHNICAL SCHOOLS 

PiTTSBUPPGH, PA. 

School or Apprentices and Journeymen 

MECHANICAL DRAniNG 



Safet-y Flange Coupling 



SCALE 5 Size 



DWG. No. C-I0I4 



LESSON No. 20. 



GE0:METRICAL problems.— Before takin- up tlie follow- 
ing |)roblem> in geometrical construction, the student should see that 
the points of his pencils and compasses are in first-class oi'der, as it is 
necessary that this work shall be done as accurately as is possible. 

The main oliject of the present lesson is to familiarize the student 
with certain geometrical terms and their meaning, all of which are 
constantlv used in mechanical drawing. This is especially necessarv 
for those students who have not studied plane geometry. 

\Mien laying out this lesson the student is expected to use the fol- 
lowing tools only: pencil, both triangles, scale, and l)oth large and 
small pencil compasses. 

Fig. I. Bisect (or divide in half) a straight line. 

Fig. 2. Bisect a gi\en arc. 



Fisr. 



Bisect a gi\cn angle. 



Fig. 4. Di\-ide a line sff inches long into 11 equal parts. 



Fig. 5. Divide the space between two lines into 13 egiial parts, 
the lines to be 2 inches apart. 

Fis;. 6. Circumscribe a circle about a given triangle. Inscribe a 
circle in the same triangle. 

Fig. 7. Through a given point draw a line tangent to a given cir- 
cle, the point being on the circumference of the circle. 

The student is expected to take all the time desired, and to study 
carefully each of these problems. The ability to 7na/!e this drawing is 
of itself of little value, but if the student fully grasps the principles 
involved in these problems and applies them to later work, this lesson 
will be of great value. 

Each student is expected to prove each problem to the satisfaction 
of his instructor. 

Do not trace this lesson, as a pencil drawing is all that is re- 
quired. 




Poini 




CL/ASS Indusir'ial trade Machinist 
NAME John W. Roberts date Nov. 20-06. 



THE CARNEGIE TECHNICAL SCHOOLS 

PITTSBURGH, PA. 

School or Apprenticeis and Joupsevmen 
MECHANICAL DRAWING 



Geometrical. Problems 



SCALE. Full Size 



one. NO. C_ 10 15 



LESSON No. 21. 



THE ELLIPSE. — Make a neat pencil drawing of an ellipse by 
the three methods indicated, and of the elliptical curve shown on 
Drawing C-1016. 

^\1len drawing the ellipse, make the major or long axis 3^ inches, 
and the minor or short axis 2 inches in each case. 

For Fig. I, lay off the major and minor axes to the lengths given 
above; take a straight edge made of any suitable material, as card- 
board or wood, and, on one edge, mark off the points AB equal to 
half the minor axis; from A, mark off point C equal to half the major 
axis. Place the straight edge so that the point B comes on the major axis 
and point C on the minor axis; now, with the pencil, mark a point on 
the drawing paper at A. Shift the straight edge and repeat (keeping 
B and C on the major and minor axes respectively), placing a sufficient 
number of points on the paper to enable you to trace a curve through 
them easily. 



The method illustrated in Fig. 2 is of such a nature that the student 
should be able to solve the problem without assistance. 

Fig. 3 is known as the "Three-radii Method." 

Construct the rectangle ADCEB. Draw the diagonal AC. Through 
D, draw DF at right angles to AC. Then, F is the center for arc 
GCH, and J is the center for arc KAL. 

Make OM=OC. Describe the semicircle AM. 

Make OP=CN. With center F, describe arc RPS. Make AQ= 
ON. Then, with J as center and radius JQ, describe arc intersecting 
arc RPS at T. T is the center for the tangent arc LG. 

To construct the curve shown at Fig. 4, divide the base lines of 
the curve into the same number of equal parts (any number) and con- 
nect these division points by straight lines. The combined outer sur- 
faces of these lines form the desired curve. 



Fig./ 




Fig. 2 





Fig. 3 




CLASS Industnal toaoc Machinist 

NAMc John IV. Roberts date Dec. /8- 06. 



THE CARNEGIE TECHNICAL SCHOOLS 

P/TTS8Uf>aH, PA. 

School of Apprentices ano JotjfiUCYMEU 

MECHANICAL DRAWIHQ 



Thz Ellipsc 



SCALE Full Si -ze 



DWG.No. CJ0I6 



LESSON No. 22, 



ENGINEERING CURVES.— The principle of this lesson is to 
generate the path of a moving point. The curves illustrated are con- 
stantly used in engineering work, and a knowledge of their construction 
should be both interesting and valuable to the student. 

The cycloid is the curve generated by a point on the circumference 
of a circle when rolled along a straight line. AVTien the generating 
circle is rolled upon another circle, an epicycloid will be generated. 

When the generating circle is rolled under another circle, a h\^o- 
cycloid will be generated. 

To generate the cycloid mechanicall}-, lay off the base and center 
Imes; set the dividers to an}' short space (so that the length of the 
chord is about equal to the arc), in this instance I inch, and step oft" 
1 6 or 1 8 points on the base line. Erect perpendiculars through these 
points; swing in the generating circle from these different points, so as 
lo place the circle in the different positions which it would assume in 
making one complete revolution. Now, with the dividers, step off on 
the second circle the distance it has rolled along the base line, in this 
case J inch. Repeat for each new position of the generating circle 
(measuring with the dividers the distance around the circle that it has 
lolled along the base line), until a complete re^■olution has been made, 
then trace the curve through the points thus found. 

The epicycloid and hypocycloid are generated in the same manner, 



the base circle replacing the base line of the cycloid. 

The involute is the curve generated by every point in a cord as it 
is wrapped upon or unwound from a cylinder. 

To develop the involute mechanically, unwind a little bit of the 
cord at a time, and step off upon the line the distance unwound. 

Set the dividers to j inch and step off lo or 12 divisions upon the 
base circle ; from these points draw tangent lines to represent the cord 
in different positions when being unwound. 

The helix or screw is the curve which w^ould be generated upon a 
cylinder revolved at a constant speed against a point, the point moving 
along at a constant speed parallel with the axis of the cylinder. 

To generate this, curve mechanically, divide the circumference of 
the cylinder into any number of equal parts, in this case 25, numbering 
these points from the left on the center line, as shown. Divide the pitch 
distance on the cylinder into the same number of equal spaces (25) by 
which the circumference of the cylinder was divided. 

Now locate points on the side view of the cylinder at the intersec- 
tion of the vertical division lines with the horizontal projection lines 
(these lines being projected from the points on the end view of the 
cylinder) ; then trace the curve through the points thus formed. This 
subject requires A-ery accurate and careful work on the part of the 
student. 



Cydcid 



Involute 




CLASi Indusfrial tradc Machinist 
NAME John W. Roberts datc Feb. 6.0T. 



THE CARNEGIE TECHNICAL SCHOOLS 
p/rrsBuffGH , PA. 
School of A^p/fCNTiccs and Journeymen 

MECHANICAL DRAWING 



Engineering Curves 
The Path or a Moving Point 

SCALE Full Size owe.No. C.I0I7 



LESSON No. 23. 



SPUR GEAR. — From Drawing C-ioiS make a full-size pencil 
drawing of the 24-tooth spur gear illustrated. 

The student should study carefully the following memoranda, as 
he is expected to make use of them in obtaining the sizes of teeth, 
diameters of gear, etc. 

If grooves are cut in the face of a smooth wheel, the parts between 
the grooves are called lands. A part added to a land is called an ad- 
dendum. A land and addendum together is a tooth. Between the 
teeth are spaces. A toothed wheel is called a gear wheel, or simply a 
gear. AVhen the teeth of two gears engage together, the gears are said 
to be in mesh. Two or more gears in mesh are called a train of gears. 
The circumference of the smooth wheel in which the grooves are cut 
and to which the addenda are added is called the pilch circle. The 
teeth of meshing gears should be so formed that their pitch circles roll 
together without any slip. The word "diameter" when applied to 
gears is understood to mean the pitch diameter, that is, the diameter of 
the pitch circle. Diametral pitch of a gear is the number of teeth to 
each inch of its pitch diameter. Circular pitch is the distance from 
the center of one tooth to the center of the next tooth, measured along 
the pitch circle. A gear blank is the wheel before the teeth have been 
cut into it. 

In modern practice the proportions of involute cut teeth are as 
follows: The tooth thickness, T, is equal to the space, S. The adden- 

1 



dum, A, is equal to 



thus for 4 pitch the addendum 



Diametral Pitch' 

i? \ inch. The clearance is generally made one-eighth of the addendum 
height; the depth, D, is equal to A, with clearance added. 

The radius, R, at the root of the tooth is about one-sixth the dis- 



tance B, but varies greatly. The rim thickness, C, is usually made 
approximately equal to tooth depth. 

USEFUL GEAR FORMULAS.— Circular Pitch or C P =2iI4i6 

■ DP • 

Diametral Pitch or D.P. = ^^^^. 



Pitch Diameter= 



CP 

Number of teeth 
DP 



Distance between the centers of two gears = i- of 



N+n 
DP 



N= number of teeth in large gear; n= number of teeth in small gear. 

Outside diameter of gear, or diameter of blank, = number of teeth 
in gear-f2-v-D.P. 

The particular involute curve most generally used in gear teeth is 
called the 15° involute. To construct it: Describe the pitch circle of 
the required gear and draw a line tangent to it. At the tangent point, 
draw a line at an angle of 15° to the tangent line. From the center of 
pitch circle, draw a circle tangent to the 15° line; this is called the base 
circle, and is the circle upon which the involute is generated. 

When laying out the gear teeth, observe that the part of the tooth 
inside of the base circle, or the flank, as it is generally termed is a 
radial line. It is necessary to lay out the involute curve but once for 
the student may set his compasses to a radius (which M-ill be an approx- 
imation to this curve), to throw in the faces of the other teeth. This 
work requires the utmost care to obtain accurate results. 

WTien pencil drawing is complete, make a good clear tracing. 

Where the dimensions are not shown, the student is expected to use 
the formulas given to obtain the necessary figures. 



True Involute 



Addendum Circle 

Pitch Circle 
Base Circle 
Roof Circle 




CLASS Industrial trade Machinist 

NAME John yv. Roberls date Man20-O7. 



THE CARNEGIE TECHNICAL SCHOOLS 

pittsburgh, pa. 
School of Apprentices and Journeymen 
mechanical drawing 



Spur Gear 



SCALE Full Size 



Diva.No.C^IOI& 



LESSON No. 24. 



SPECIFICATIOX.— This lesson is for the purpose of helping the 
student to de\ elop the facuhy of making mental pictures, to force him 
to make a drawing of something not shown, but for which it is neces- 
sary for him to use his imagination. 

From the following data make a half-size two-\iew mechanical 
drawing of the cast-iron puUev described. For the sectional view use 
the conventional method described in Lesson No. 14 on the hand 
wheel. 

Diameter of the pulle\- 1 foot 2 inches at the crown (or greatest diam- 
eter); face or width 6 inches; taper of crown equals \ inch per foot. 

Diameter rf hub 3! inches; length of hub 4 inches; bore i|- inches; 
with ke\^vay y^ inch wide b\- -f^ inch high. 

Rim to be made with rib around inside where joined to arms. Rim 
\ inch thick at edge, and -^-g inch thick through crown and rib; inside 
of rim to be straight to arms. 

Number of arms 6; arms to be \\ inches wide bv | inch thick at rim, 
and 1 1 inches wide by jf inch thick at hub; j-inch fillets (or rounded 



comers) at side of arms at hub, and at side and edge of arms at the 
rim; |-inch radius at the junction of the arms near the hub. 

\\'hen locating the keyway in the side view showing the end of the 
hub, be sure to place it central with one of the arms, as this will give a 
stronger hub section than if the kevwav is placed midwa\" between two 
arms. 

The student is expected to first make a freehand sketch of the two 
views of the pulley. On this sketch lie should place all the dimen- 
sions given above, and then use the sketch as a guide when laying out 
the working drawing. It is assumed that the student will tn,- to study 
out this lesson without looking at a model in the shop, so that he may 
derive the greatest benefit from his efforts. There is no objection to 
the student examining a model aj!cr he has finished his freehand 
sketch to the satisfaction of his instructor. 

!Make a tracing of the finished pencil drawing, tlie title to Ije 14" 
Pulley, Drawing C-ioiq. 

Take plenty of time and get all possible from this lesson. 



LESSON No. 25, 



CONIC SECTIONS.— The fundamental principle involved in this 
lesson is the projection of a point. 

A thorough kno^vledge of tliis subject is of great value when draw- 
ing pieces of such shape that it is difficult to project correctly the neces- 
sary views. From this lesson and from Lesson No. 22, the student 
should realize that curves and circular figures may be projected in a 
very simple manner if taken point by point. 

The figures shown on Drawing C-1020 illustrate a cone cut by a 
plane in two different ways. \Mien a cone is cut by a plane which 
passes between the apex and the base at any angle, the section will be 
an ellipse. If the cone is cut by a plane which is parallel with one 
side, the section made is a parabola. 

Lay out the cones to the dimensions given. Divide the base circle 
of the top view into any number of points equally spaced; from these 



points draw lines to the apex; now project the lines down onto the side 
view. 

To develop the ellipse, cut the cone as shown; the points made by 
the intersection of the cutting plane with the slope lines should then be 
projected to the same lines in the top view. By connecting these points 
we have a true ellipse. 

The top view of the parabola is projected in the same manner as 
the ellipse, ^^'ith the top and side views complete, it is quite a simple 
matter to develop the front view point by point, as shown in the illustration. 

By this method of projection the student can easily lay out the para- 
bolic curve in the front view first, and then draw the cone around the 
curve. 

Do this work very carefully, as one of the valuable points to be 
gained from this lesson is the abilitv to do accurate worL 





Ellipse 



Parabola 



Cla.%% incosfrial trade MacnJniSf 

name: John W. f?ot>erfs date Mar.28- 07. 



THE CARNEGIE TECHNICAL SCHOOLS 

PITTS3U^e~, PA. 

School FOR Apprels- CEiS a^o JOuPHE:YntE,\ 

MECHANICAL. DPAWING 



Conic Sections 



sc/=iX fl/ ■ S'ze 



d.:g. ko. CI 020 



LESSON No. 26. 



INTERSECTIONS. — The important principle contained in this 
lesson is the projection of a point. 

From Drawing C-1021, make a full-size pencil drawing of the 
intersecting cylinders and their developments. 

The curve formed by the intersection of the two c}linders is found 
point by point as shown by points 2 and 4 on the illustration. The 
oval shown in the end view is formed by cutting the large cylinder off 
at an angle of 30° with the horizontal plane; it is found in the same 
manner as the curve of intersection. 

If the student studies the illustration carefully, he should be able to 
follow out the method of projecting a point from one view to 
another. 

As the end views of the cylinders are the only views on which the 
true circumference can be obtained, it naturally follows that it is the 
end view in each case that should be used to locate the division points. 

The circumference of the cylinder may be divided into any num- 
ber of points, and those points projected upon the other views to obtain 
the desired curves. 



DEVELOPMENT.— The student should try to realize that a sur- 
face is composed of a series of lines. 

The different methods of developing a surface are usually described 
by the kinds of lines used for this purpose. As an instance, in our 
present lesson we use parallel lines to develop the surfaces of the 
cylinders. 

If we were to cut the large cylinder through at point C, and were 
then to spread it out flat, we would have a duplicate of the develop- 
ment of the large cylinder shown. 

For the reasons given above, the end view of the cylinder is the 
proper place to obtain the true length of the development, assuming 
that the student is unable to find the circumference by simple arith- 
metic. 

The lengths of the various lines used in developing the surface of 
the pattern may be obtained from the side view. 

It is very desirable that each student should make a careful study 
of this subject, as a thorough knowledge of the principle involved will 
be of value when drawing difficult shapes. 



IZ I 3 i 4. 5 6 7 B S 10 II IS 




c d e { g 1^ J k m n a be 



CLAS^ Industrial trade Machinisf 

name: John W. Roberts date April SO-Oy. 



THE CARNEGIE TECHNICAL SCHOOLS 

PITTSBURGH, 'l>A. 

School of Apprentices and journeymen 
mechanical drawing 



Intersections and Developments 
Parallel Line Development 



SCALE Eull Size 



OtVG. No. C 1021 



LESSON No. 27. 



INTERSECTIONS.— From Drawing C-1022, make a full-size 
pencil drawing of the intersecting cone and cylinder and their develop- 
ments. 

If the student has fully mastered the previous lesson on intersections, 
he should be able to develop the curves of intersection shown in the 
top and front views of the present lesson. These curves are found in 
the same manner as those of the intersecting cylinders; that is, point 
by point. 

The student may divide the end of the cylinder into any number of 
points, then draw radial lines through these points. Or he may draw 
the radial lines first, and then place ])oints at the intersections of the 
lines with the end of the cylinder, as shown by points i and 4. 

The latter method is the one used in the illustration, and the stu- 
dent should observe that to project these points i and 4, it is first 
necessar\' to have the radial line 1-4 projected upon the top 



view. 



RADIAL-LINE DEVELOPMENT.— In our last lesson the sur- 
faces of the figures were composed of parallel lines, the method of 
development being named from the kind of lines used. 

In our present lesson we find it necessary to use radial lines to 
develop the surface of the cone, from which this method derives the 
name of "Radial-line Development." 

When la)'ing out the development of the cone, the student must 
bear in mind that the true length of the lines on the cone can be found 
on the sides of the cone only, as in all other positions the lines are fore- 
shortened. Thus to get the true distance from the apex of the cone 
to point I, this point must be projected to one of the sides. 

The length of the arc of the development is equal to the circum- 
ference of the base of the cone. 

The radial lines used in finding the intersections are also used in. 
locating the opening in the development. 

Do your work very carefully. 




CLASS Indusfr'ial trade Machinist 

NAME Jolin Y/. Roberts date April 26,07. 



THE CARNEGIE TECHNICAL SCHOOLS 

pittsbursh, pa 
School of Apprentices and Journeymen 
mechanical draining 



Intersections and Developments 
Radial Line Development 



SCALE Full Size 



OYta. NO. C. 1022 



LESSON No. 28. 



TRIAXGULATION DEVELOPMENT.— Upon a B-size sheet 
of drawing paper (i5"X22"), make a full-size pencil drawing of the 
Transition Piece and its development. 

Sheet-metal workers require a great many patterns which cannot 
he laid out to good advantage by either the Parallel- or Radial-line 
methods of develo]Dment. 

These patterns may usually be laid out by dividing the surface of 
the figures into a series of triangles, from whicli this method gets the 
name "Triangulation Development." 



LESSON. — First lay out the two views of the piece illustrated, 
marking them with letters and figures as shown. Then find the true 
length of each of the slope lines ABCD, etc. These lengths may be 
found in the manner indicated on the illustration, which the student 
should be able to understand without help. 

Now, using these lines with the top and base lines, construct the 
triangles into which the figure had been previously divided. Connect 
these triangles in the manner indicated by the partial development, 
and the result will be the complete pattern desired. 




True lengfh 



CLASS Industrial trade Machinist 

NAME John W. Roberts date tvlay 6^07. 



THE CARNEGIE TECHNICAL SCHOOLS 

PITTSBURGH, PA. 

School or ApPf?E>^T/c£:s and joupneymcn 

MECHANICAL DRAWING 



Intersections and Developments 
Triangulation Development 



SCALE Full Size 



o WG. Wo. B- 1023 



LESSON No. 29. 



SPECIFICATIOX.— This lesson, like Lesson Xo. 24, is intended 
to strengthen the student's facuhy for mental picturing, and to give him 
confidence when M'orking from a ^^Titten description or specification. 
Another object is to help the student to become more familiar with the 
rules for laying out spur gears. 

The student may refer to Lesson Xo. 23 if he has forgotten the 
rules for spur gearing; he should study these rules carefully, as a 
thorough knowledge of this subject should prove of great \alue. 

From the following data make a half -size pencil drawing and trac- 
ing of a 15° involute spur gear. 

The gear to have 28 T., 2 D.P. Face or width 3^ inches. Hub 
central with face, with 2-inch bore, 3^-inch diameter, and 5 inches long. 
Ke\T\-ay ^ inch wide by -^^ inch high. Web, or part connecting hub 
with rim, to be f inch thick and central with face. |-inch fillets at 



junction of web with hub, and of web with rim. Round inside ed^es 
of rim with ^-inch radius. Hub to have sharp comers. 

The student should first make a freehand sketch of a sectional view 
of the gear. On this sketch place aU the dimensions given above. Xow 
calculate all the necessary dimensions which are not given, such as 
diameter of pitch circle, blank diameter, circular pitch, etc. 

M students are expected to do their work in a methodical manner, 
first making the sketch and the calculations, and then working from 
both to make the finished workinsr dra\^-ins. 

It is a valuable faculty to learn to be systematic in all your work, 
as much valuable time will be saved to your employer, and fewer mis- 
takes will be made. 

The title of this drawing is "Spur Gear," Drawing Xo. C-1924. 



LESSON No. ^,o 



T?E\'KL GEARING. — Gear wheels are constantly used for trans- 
mitting motion between shafts. AMien the axes of the shafts are 
])arallel, spur gears are generally used; it frequently happens, how- 
ever, that the shafts are not parallel, but are placed at an angle with 
each other, in which event it is necessary to use a dilTerent kind of- 
uear wheel. Be\el gears are well adapted for use under such condi- 
tions, as they can be used to good advantage at practically all angles. 

When the "ears are the same size and the shafts are placed at 
right angles, they are called "mitre gears," but when one of the wheels 
is larger than the other, it is described as the "gear," while the smaller 
is called the "pinion." 

In general drafting-room practice it is customary to show only 
sectional views of bevel gears, as any other views are as a rule unnec- 
essary, and considerable time and expense are thereby saved. 

On Drawing €-1025 is shown a sectional view of a gear of 40 T., 
4 D.P. in mesh, with a pinion of 20 T., 4 D.P. The student is ex- 
pected to make an accurate pencil drawing and tracing of this subject. 

The i)itch diameters are found in the same manner as in spur 
gearing, but are measured at the points indicated on the illustration. 

To construct the gear and pinion illustrated : first lay out the 
center lines, then draw in construction lines representing the pitch 



diameters. From the intersection of the center lines draw radial lines 
cutting the intersections of the pitch diameter lines. These radial 
lines are also pitch lines or neutral lines of the tooth. 

The addendum height, depth of tooth, clearance, etc., are found 
as in spur gearing, but these measurements are taken along line A-B, 
which is at right angles with the radial pitch line. 

Assuming that the student has no knowledge of the trigonometric 
functions, or the solution of triangles by plane trigonometry, it is ex- 
pected that each student will lay out this lesson with great care, so 
that the blank diameters of the gear and pinion may be obtained by 
scaling the pencil drawing. The various angles, as the turning and 
cutting angles and angle of edge, may be found in the same manner, 
using a protractor to measure the angles. Later, when the student 
has received some instruction in plane trigonometry, he will be required 
to calculate these diameters as well as the various angles given. 

The keyway is f inch wide by \ inch high in both gear and pinion. 

Note carefully the method of dimensioning these gears; the drafts- 
man must always keep in mind the needs of the pattern maker and 
machinist in all his work. He should be familiar with the various 
sliop operations of machining the pieces he illustrates, otherwise it is 
rather difficult for him to dimension a drawing intelligently. 



■ Blank Diameter 



k 
11) 

I 
Q 

i 



Q 



Pitch Diameter - 




C£/>ss Industrial trade t^achinisf 

NAMc John 'M. Roberta date IVIay 12-07. 



THE CARNEGIE TECHNICAL SCHOOLS 

PirrSBURGH, PA. 

School or apprentices and Journeymen 

MECHANICAL DRAWING 



Bevel Gears 



SCALE Full Size 



oma. No, C-i095 



LESSON No. 31 



VALUE OF PRACTICE.— From the previous lessons the stu- 
dent should have become familiar with the general principles of 
mechanical drawing. With this assumption in mind, the main 
requirement of the student is now to obtain sufficient practice, making 
detail and assembly drawings, to help him to become proficient in 
turning out rapidly work that is accurate, with the lettering and dimen- 
sioning done in a neat and attractive manner. 

No modern drafting room will send out blue prints of drawings 
upon which the lettering has been poorly done, or the dimensions of 
which are indistinct. Many a young draftsman has been refused em- 
ployment simply because he was a poor letterer. If the applicant's 
sample drawing is neatly lettered and dimensioned, the chances are 
tliat he will be given an opportunity to show what he can do. 

The student is expected to do the very best work he is capable of, 
on the following working drawings. 

DETAIL DRAWING. — The present lesson is a quarter-size 
detail drawing of the lathe leg shown on Drawing C-1026. Make a 



tracing of the finished pencil drawing. 

The student will observe that the metal of the side of the leg is 
I inch thick near the back, and that it tapers down to I inch at the 
front edge. This is shown in the top view, and is for two purposes: 
To make the casting light but strong, and also to allow the pattern to 
be easily lifted out of the sand when making molds in the foundry. 

The openings in the back of the leg are for the purpose of making 
the casting lighter. The J-inch rib around these openings strengthens 
the casting without adding much weight. 

To throw in the large radii given, the student will find it necessary 
to use a beam compass, as these radii are too long for the ordinary 
compass, even though the extension bar were used. 

In most drafting rooms a mark of some kind is used on the draw- 
ings to indicate that a surface is to be finished, that is, machined in the 
shop. The "finish mark" shown on the present lesson is adopted 
from the Universal Dictionary of Mechanical Drawing by Prof. G. 
H. Follows, 




Finish mark 

i- 



4 



"^^^ 



•o<o 



-^ 



f-^ 



-?3 



^y 



-H 









<^''- 






Holes 



Bill of Material 



Item 

No. 


Description end Male rial 


Pal. No. f?eg. 


'0^ 


Leq C.I. 


70 ^ 



T 



-Ji_13 



fe Holes in -feef 
Sec lion A ^3 



CLASS Industrial trade: Machinist 
NAMC John W. Roberts date: May fl_ 07^ 



THE CARNEGIE TECHNICAL SCHOOLS 

PlTTQBUf?GH^ PA. 

School of Apprentices and journeymen 
mcchanical drawing 



12 Speed Lathe 
Leg Details 



SCALE J- Size 



owe. No. C-I02& 



LESSON No. 32. 



LATHE BED. — ^Make a half-size pencil drawing of the lathe bed 
shown on drawing C-1027. Make a tracing of the finished pencil 
drawing. 

This drawing shows the method commonly used to take care of 
pieces which are too large for standard-size sheets; this method is to 
show the piece "broken," as it is termed. 

The lathe bed shown is five feet long, and to show it without " break- 
ing," or the complete bed, would necessitate that it be drawn to a very 
small scale, so small, in fact, that the views would not show to the best 
advantage what the drawing was intended to show. 

By breaking away part of the bed, we are able to draw it to a larger 
scale and show more clearly its shape and size. The part broken 
away is of no value to any one using the drawing, as it is similar to the 
rest of the bed adjoining the break. 



Observe carefully all notes and dimensions, and see that none are 
overlooked, as full information must be furnished on working drawings. 

The cap screws referred to in the "Bill of Material" are for bolting 
the legs to the bed. 

The broken ^■iews of the top and bottom of the bed are intended 
to show more clearly the shape of the corners, the sizes of fillets, and 
to show the position of bolt holes. 

The student should refer to the leg drawing, C-1026, if he desires 
to see whether the positions of the clearance holes in the top view of 
the leg correspond to the tapped holes in the bottom of the bed. 

Observe the method of using the "finish mark" shown at the top 
of the end view. This indicates that the whole surface between marks 
is to be finished. 




Drill, ^ dia^ deep 
Tap f-l6Thds. 



Bill or Material 



/ 



Item 
No. 


Description and Material 


Pat No. 


Reg. 


'^ 


Bed C.I. 


71 


1 


C2J 


ixiiHex.Hd. Cap 5c. 




6 



CLASS Industrial nrAoe Machinist 

NAME John W. Roberts datc Afay 10-07. 



THE CARNEGIE TECHNICAL SCHOOLS 

PITTSBURGH, PA. 
SCHOOL OF APPf^NTICES AND JOUHSCYNIEN 
MECHANICAL OKAWING 



12 Speed Lathe 
Bed Details 



scALC 4 Size 



dwg.no. C.I 027 



LESSON No. 33. 



TOOL-REST DETAILS. — Most of the parts or details of a 
speed-lathe tool rest are shown on Drawing C-1028; part of these 
details are drawn half size, and the rest full size. 

Make an accurate pencil drawing and tracing of the details shown. 

The hand wheel is ver\' similar to one drawn in an earlier lesson, 
with the exception that it is an "offset" wheel, that is, the rim is not 
central over the arms, but set to one side. The necessary radii with 
the location of their centers are shown, so that the student should be 



able to draw this hand wheel without difficulty. 

When drawing the arms of the hand wheel, bear in mind what was 
said in the earlier hand-wheel lesson, in regard to using a straight line 
for the purpose of joining two curves. 

Do not overlook any of the dimensions on the various details, for 
you must remember that you are furnishing the man in the shop with 
the necessary information to machine these parts correctly. 

Use great care with the lettering and figures. 



Finish all over 




Drill §'-Tapf-ll Thd. 



^'£— 


"^ 


7 
J2 


■* 


' 1 
1 1 
1 / 


— 
T . 






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.Illiif 



XJl 



\ 





•^l (^ 



IIThd.per in. y>~ 



m 



B3 (c^Ht$ 




l6Thd.per in. 



Rivet 



Harden 



CLASS Industrial trade Machinist 

NAME John W. Roberts datc Dec. IS^07. 



THE CARNEGIE TECHNICAL SCHOOLS 

PITTSBUKeH PA. 

School of AfP/fENTicES Afio Jouknevmen 
MECHANICAL DRAWING 



12 Speed Lathe 
Tool Rest Details 



SCALE g & Full Size 



owa.No. C/023 



LESSON No. 34. 



TOOL-REST ASSEMBLY.— Drawing C-1029 is an assembly 
drawing of the complete tool rest. 

This drawing is used for the purpose of showing how the different 
parts are fastened together, or assembled, as it is termed. 

The only parts dimensioned are the stand and clamp, all of the 
other details being machined from Drawing C-1028. This assembly 
drawing is, therefore, used as a detail drawing also, as the stand and 
clamp may be machined from it. 



When drawing the parts that are not dimensioned, the student must 
necessarily refer to the detail drawing to obtain the sizes needed. 

Study the drawing carefully so as to obtain a clear understanding 
of the meaning of each line. Do not simply copy the various lines 
because they are shown on the original; satisfy yourself as to their 

aning. 

Think for yourself. 




Section A.B 



De/a'/l of Stand 



Drill ^-Tapi-16 Thds. 




J" 



Bill or Material 



Item 
No. 


Description and Material 


Pat. No. 


Req. 


(z) 


Tool Pest, C.I. 


79 




® 


' Stand, C. 1. 


80 


/ 


@ 


" Base, C.I. 


8/ 




@ 


■■ Hand Wheel. C.I. 


82 1 




@ 


■■ Clamp, W.I. 






® 


Clamp Bolt, W. 1. 






® 


Adjusting Screw, C.R. 






® 


Adj. Screw Lever, C.R. 


. 





Ci'«ss Industrial trade Machinist 

NAME John VJ. Roberts date Dec. 24-07. 



THE CARNEGIE TECHNICAL SCHOOLS 

pittsbukgh, pa. 
School or Apprentices and Journevmen 

MECHANICAL. ORAWING 



12 Speed Lathe 
Tool Rest A ssembly 

SCALE J Size DWG. No. C. 1023 



LESSON No. 35, 



TAILSTOCK DETAILS.— Part of the details of a lathe tailstock 
are shown on Drawing C-1030. 

The sectional view of the spindle shows the taper bore in one end, 
and the method of fastening the bronze nut in the other end. 

The end of the spindle is bored to a taper of | inch per foot, or the 
"Morse Taper," a name by which this particular taper is known in 
shops and drafting rooms. By a taper of | inch per foot, we mean 
that a cylindrical piece 12 inches long and i inch in diameter at the 
small end will be if inches in diameter at the large end. In other 



words, the piece is | inch larger in diameter at one end than at the 
other. 

By this time the student should be sufficiently familiar with hand 
wheels to need no instruction on this subject. 

The binding screw shown is an illustration which shows the value 
of a knowledge of shop practice. This screw is machined in a lathe 
in the manner shown by the solid lines; after being finished, it is placed 
in a special forming tool, where it is bent to the shape shown by the 
dash lines. Make a tracing of the finished pencil drawing. 




No 2 Morse Taper 



-gTap 8 R.H.Sq.Thd 



-// 



T 



4r^.- 






"5|5 



zf 



ixis Pin. Re a. 2 




w§m 



16 Thd. per In. 



CLASS Indusfrial trade Machinist 

NAME John W. Roberts date Dec.30-07. 



THE CARNEGIE TECHNICAL SCHOOLS 

PITTSBURGH, PA. 

School of Appffcrmccs and Journcymcn 

MECHANICAL DRAWING 



/P Speed Lathe 
Tailstock Details 



SCALE Full Size 



Dwa.Na. C-J030 



LESSON No. 



36. 



TAILSTOCK DETAILS.— The rest of the details of the lathe 
lailstock are siiown on Drawing C-1031. 

The square-thread screw is used to move the spindle in and out of 
the tailslock barrel. The manner in which the thread is shown on 
the .screw indicates that it is to l)e cut the full length to the collar. 
The main oliject in showing the thread in this manner is to .save the 
draftsman's time. 

The small key set into the stem of the screw is known as a Wood- 
ruff key. This key resembles a portion of a washer driven into a slot 
milled in the screw. 

The small T-shaped key shown is the spindle key, and is used to 
pre\ent the spindle from revohing. 

The wrench shown is used to tighten the nut on the clamp bolt, 
thus fastenini; the tailstock to the bed. 



The tailstock plug, or bell as it is usually termed, is screwed into 
the rear end of the tailstock barrel for the purpose of supporting the 
spindle screw. 

The center illustrated is made of tool steel and hardened. Two of 
these centers are used on each lathe, one being fitted into the tail- 
stock spindle, the other in the nose of the headstock spindle, the 
former being known as the "dead center," the latter as the "!i\e 
center." 

The stem of the center is turned to a taper of | inch per foot, or 
what is known as the Morse taper. 

The small steel oiler is used to drop oil on the centers. 

When making a pencil drawing and tracing of this lesson, do the 
very best work of which }'ou are capable. 



/o 



I / 

14 



-1S5 



1=1 



1 






H 



-aR.H.Sq. Thd. 



->i 



're 



J L 



N<\i- 



L 7' I Sfi I 



/6 Thd. per in. 



Ill 



5 
6 



i T 



i ^^^^iir 



B'^IS 



rm 





■~T 



CLASS Indusfrial trade Machinist 

NAME John W^. Roberts date Jan. 6.08. 



THE CARNEG/E TECHNICAL SCHOOLS 

pittsburoh, pa. 
School of Apprehtices and journeymen 
mechanical drawing 



12 Speed Lathe 
Tailstock Details 

SCALE Full Size owe. no. C_ IOS/ 



LESSON No. 37. 



TAILSTOCK ASSEMBLY. — Drawing C-1032 shows the tail- 
stock completely assembled, with all the details numbered to corre- 
spond with the nimibers in the " Bill of Material." 

\\Tiere dimensions are not shown on certain parts, the student is 
expected to refer to the detail drawings for the necessary informa- 
tion. 

The saw cut on the side of the tailstock barrel is for the purpose of 



allowing this part to clamp tightly around the spindle when the bind- 
ing screw is tightened down. 

The oil hole shown in the bell should be drilled after it is in place 
in the barrel, as it should of necessity be on the upper side of the bell. 

Make this drawing and tracing very carefully; do not overlook any 
dimensions or notes. Bear in mind that nothing is good enough but 
the best M'ork you are able to do. 



Bore l£ Tap 1^-12 Thd. 




Bill of Material 



Note: For details see Dwgs. C.I030 3; C.I03I 



'^nT< Description and Material \PatNo\f?eq. 


{D Tailstock. C.I. \ 76 ! / 


@ Spindle, Corona Steel 






® Screvv C.R. with i'Hex. Nut. 






<?? 


Bell, C.I 


77 




@ 


Hand Wheel. C. 1. 


78 




® j Dead Center, Tool Steel 






(7} Spindle Nut. Bz. 






® i,fr/ Woodruff Key, C.R. 






® ii VJasher, C.R. 






® 


fsYuKi Spindle Key. C.R. 






QD 


Oiler, C.R. 






@ 


Binding Screw, C.R. 






@ 


fx 6 Clamp Bolt with Hex. Nut 






<(^^ 


Clamp , yv. 1. 







CLA^i Industrial trade Machinist 
KAue John W. Roberts datz Jan. IP-OS. 



THE CARNEGIE TECHNICAL SCHOOLS 

Pittsburgh, pa. 
School or APPffCh/TfCcs and Joupnc^mzn 

MCCHAhllCAL DffAWIf^G 



/ 2 Speed Lathe 
Tailstock Assembly 

scALt. J Size DWG. i^o. C.I032 



LESSON No. 38. 



HEADSTOCK DETAILS.— Several of the details of a lathe 
headstock are shown on Drawing C-1033. 

The cone pulley has four steps, or different diameters, giving four 
different speeds to the lathe spindle. Each step is made with its 
greatest diameter at the center; this is called "Crowning," and as a 
belt will naturally run on the greatest diameter, this is of value in 
keeping the belt on the pulley. 

The diameters given are at the crown, which is of | inch greater 
diameter than at the sides of each step. 

The machine work on the spindle must be very carefully and 



accurately done; the journals and the inside of the nose end should 
be finished by grinding. The spindle is bored to allow for the center's 
easy removal, the "nose" end of the hole being tapered to suit the 
center shown on Drawing C-1031. 

The spindle and the cone pulley are keyed together by means of 
a if -inch Woodruff key. 

The end motion of the spindle is taken up by means of the spanner 
nut, and the wear is taken by the hardened steel collar and washer 
shown on the small end of the spindle. 



Crown = J on dia. 



IBThd.per In. 




■ /' I 
■'4 I 6Thd. per inch 

U.S.Sfd. 



CL/^ss Industrial ti?a.dc Machinist 
NAM£ John W.Roberts oatc Jan. 16.08, 



THE CARNEGIE TECHNICAL SCHOOLS 

PITTeBURSH, PA. 

School or Apppemtices and JoupseyMCN 

MECHANICAL DRAWING 



12 Speed Lathe 
Headstock Details 



SCALE 4 Size 



DWG.r^a. C-/033 



LESSON No. 39. 



HEADSTOCK ASSEMBLY.— The assembly drawing of the 
lathe headstock illustrates the final detail of the speed lathe. From 
Drawing C-1034, make a half-size pencil drawing and tracing. 

The headstock casting and the bearing caps are detailed on this 
drawing; thus it ma\- be used l)oth as a detail and as an assembly 
drawing. 

The bearings of Baljljilt metal are cast solidly in the headstock 
and caps, being held in place l)y the collar and dovetails shown. 

Oil cups are screwed into the caps, the oil being carried along the 
oil grooves the length of the bearings, thus keeping them well lubri- 
cated. 



The headstock is fastened to the bed by means of cap screws, two 
being used at the front end and one at the rear end. Refer to the 
lathe-bed drawing to make sure that the positions of these screw holes 
coincide with those shown on the bed. 

Lay out the "Bill of Material" carefully; make sure that no items 
are overlooked, as this must be complete to be of real value. 

Try to get a clear understanding of all these lathe drawings and 
of the relations between the different parts; copy nothing blindly, but 
study each detail carefully, so that you may derive the benefit one is 
sure to obtain who thinks for himself. 



Drill a for i pipe tap to suit 'O Oil 
[See page 366 Machinists Supply 




Note: Oil Grooves in Headslock and Capsjz deepx^ wide 
For Headsfock details see Dwgs. CJ0J3 5 C-I03I 



CLAS% Indusirial trade Machinist 

NAxtr John VY. Roberts date Feb. 6- 08. 



THE CARNEGIE TECHNICAL SCHOOLS 

PITTSBURGH, PA. 

School or Apppentices a\d Joupnevmen 

MECHANICAL DfPAYilNG 



12 Speed Lathe 
Headstock Assembly 

SC/1LE ^ Size owG. /Vo. C-1034 



LESSON No. 40. 



SPECIFICATION. — The various details of a 12-inch speed lathe 
have been shown on the pre\'ious drawings; from these detail draw- 
ings the student is expected to get the necessary information to la\- 
out a complete assembly drawing of the lathe. 

This drawing shoidd be placed on an "A "-size sheet (22"X3o") 
and drawn to a scale of { size, showing two views — the front and the 
headstock end preferably. 

Do not show any hidden parts, but draw to scale all parts that 
would be seen from the front and end of the machine. 

The onh' dimensions that need be shown are the length and width 
at the feet, and the distance (on the front view) from the inside edge 



of the flange of the small end of the cone pulley to the outside of feet 
at the headstock end. 

These dimensions are of value for laying out the floor plan of a 
shop and in locating the countershaft in the proper position. 

The main value to the student in such a drawing is that he will 
make an assembly drawing of something he has not seen, and he will 
obtain a better and clearer understanding of the relation between the 
various parts of the machine when he has put them together on paper. 

;N[ake a tracing of the finished pencil drawing, the title of which is 
12-inch Speed Lathe Assembly, Drawing A-1035. 



LESSON No. 41. 



STANDARD DATA.— In Lesson No. 17 reference was made to 
(lata sheets, or drawings, that are used to furnish standard informa- 
tion. In most modern drafting rooms, this reference information is 
placed on a standard-size sheet, so that these sheets may be kept in 
book form. 

These data sheets are of great vakie to the draftsman for reference 
purposes, as they save time and labor; they are also of value in the 
production of drawings of uniform appearance. 

The main object of the present lesson is to familiarize the student 
with this method of preparing reference matter in condensed form, so 
that it is readily available for use. 



Information placed on these sheets must first of all be absolutely 
accurate. The sheet should be designed so that the desired informa- 
tion can be readily found, and the sheets should be of a uniform size, 
so that they may be bound together. 

The dimensions given are for a sheet the size of which is conve- 
nient to illustrate a very wide class of subjects. 

The subject-matter on the data sheet shown is U. S. standard 
screw threads, the sectional view indicating the shape and the propor- 
tions of this thread. 

]Make a pencil drawing and tracing of this lesson. 



« 

^^^ For binding, trim print fo this fine 




1-0^ 


^ 










.J 




U.S.Standard Screw / hreads 












^'«- 


Bolt 
Diameter 




DIa. at Root 
of Thread 


Tap Drill, giving 
clearance of j 
ttie freight of 
thread triangle 


Area at 
Root of Thd. 


Safe Load of 
Boll.Based on 
fibre stress of 
eOOOIbs.per sq.in. 




-P- 




2 






3*^^- 


/^' 


Indies 
1 


Indies 


1 


Indies 


Nearest 64th. 


Inches 


Nearest 6^th. 

13 


Sq.in. 


Pounds 




i{=¥¥=?= 


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N=^ 


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s 

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.620 


i 


.642 


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1810 


(Depth! of Thd. H=PX.6495 

Root dia.R=D-^ 'f/ r 

NbrThds. per m. 

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THE CARNEGIE TECHNICAL SCHOOLS. Pittsburgh, Pa. s djo36 





Ci.><ss Industrial trade tvlacbinist 

NAME John W.Roberts date: Dec. 7..07. 



THE CARNEGIE TECHNICAL SCHOOLS 

PITTSaUKGH. PA. 

School or Apprentices and Journevmem 

MECHANICAL DRAWING 



Standard Data 



owe. NO. C- /03S 



LESSON No. 42. 



C0:MP0SITE DRA^^•ING.— Any method of laying out work in 
the drafting room which reduces the general expense of producing 
drawings is to be commended. By using what are known as "com- 
])osite drawings," we sa\e making a large number of detail drawings. 

Firms that manufacture a standard line of machines usually design 
them in such a manner that the details of these machines are just 
alike e.\ce])t as to size. This being the case, a drawing can be made 
wlu'ch represents all sizes of a particular detail. As it would be im- 
]K)Ssible lo place the dimensions of all sizes on this one figure, letters 
are used to designate the various dimensions. 

Below the drawing of the piece a tahle is laid out with these letters 
as headings, and under each letter are the dimensions, for that part 
represented by the letter, for each size of the piece illustrated. 



As an illustration of the saving by this method, the present lesson 
is a composite drawing of a tap-bolt wrench; there are dimensions of 
twelve sizes shown; this one drawing then takes the place of twelve, 
and after one is familiar with the method, it is as readily and easily 
used as a separate detail drawing. 

These drawings are of value for reference purposes, and can be 
prepared on the same size sheets as standard data, and can be used as 
such. They can he furnished to the shop men who machine the parts, 
and any notes as to material, finish, etc., can be placed upon a draw- 
ing of this kind, as well as upon any other drawing. 

Make a pencil drawing and tracing of this lesson. Use care to 
make all of your figures clear and distinct, as there should never be 
an\- doubt as to a dimension. 



o 
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THE CARNEGIE TECHNICAL 


SCHOOLS 


, P lit 51 


ourgh. Pa. 


CD- 1037 



CLASS Industrial trade Machinist 
NAMc John W.Roberts date Dec. 8^07. 



THE CARNEGIE TECHNICAL SCHOOLS 

PITTSBURGH, PA. 

School or Apprl:i^t/ccs and JouRNCyMCN 

MECHANICAL. DRAWING 



CoMPosirE Drawing 



Scale 



Dtva.No. C-tOJ7 



LESSON No. 43. 



BENCH GRTXDER DETAILS.— Part of the details of a Bench 
Grinder are shown on Drawing C-1038. These details are shown in 
the same manner as they would be on a regular working drawing. 
The main object of this and of the following lessons pertaining to this 
machine is to give the student additional practice in making working 
drawings, so that he may acquire the mechanical skill necessary to the 
able draftsman. 

The steel spindle shown has two grooves turned in each of the 
journals; these grooves are not entirely filled with the Babbitt metal 
of the bearings, and this space, being filled with oil, is of considerable 
value in keeping the journal well lubricated. 

One end of the spindle is threaded for a right-hand nut and the 
other end for a left-hand nut. This decreases the ])ossibility of the 
nuts unscrewing and allowing the emery wheel to fly oft". 



The pulley should be a "driving fit" on the spindle to obtain the 
best wearing results. 

Two collars are required — one on the outside of each bearing. 
These collars help to keep emery dust out of the bearings and also 
prevent "end play" of the spindle. 

The "work rest" is a wrought-iron plate riveted to a cold rolled- 
steel stem. This "work rest" can be raised or lowered, and is held 
at the proper height by a thumb screw in the "rest stand" which sup- 
ports it. 

The material of the rest stands, the collars, and the pulley is cast 
iron. 

Make an accurate pencil drawing and tracing of this lesson. 
Do the best work of which you are capable on all of these draw- 
ings. 




CLASS Industrial trade Machinisf 

NAMc John W.Roberts date Dec. 10-07. 



THE CARNEGIE TECHNICAL SCHOOLS 

pittsburgh, pa. 
School for Apprei^ticeis and Journevmen 
mechanical drawing 



Bench Crinder Details 



SCALE p Size 



DWG. MO. C.IC3Q 



LESSON No. 44. 



BENCH GRINDER DETAILS.— The rest of the details of a 
Bench Grinder are shown on Drawing C-1039. 

The cast-iron frame has split bearings, the illustration showing the 
wearing surface of Babbitt metal cast solidly in the frame and caps. 
The Babbitt metal is held in place by circular anchors cored in the 
caps and frame. 

A felt washer is set into the sides of each bearing for the purpose 
of keeping emery dust out of the bearings. 

The circular ribs of Babbitt metal fit into the grooves of the spin- 
dle shown on Drawing C-1038. These ribs do not entirely fill the 
grooves, thus allowing a film of oil to be carried, which helps materially 



in keeping the journal well lubricated. 

The oil supply for the bearing is furnished by an oil cup which is 
screwed into the top of the cap. 

Where the caps are fitted into the frame, no "draw" is allowed; 
this is an additional precaution to keep emer\' dust away from the 
bearings. 

Do your work well. Do not be satisfied with what you consider 
"good enough"; nothing but the very best that you can do is likely 
to be acceptable to the chief draftsman. 

The design for this grinder was taken from the "American Ma- 
chinist." 



Tapi~/5Thds. 



Section A.B 




^ 



<3o 



Drill g^ for g pipe tap 1o suit Oii Cup. 
[See page J66 Machinists Supply Caf.\ 



L. ,L 









\<r 



■'/6 



Core for two circular babbitt ancfiors 
in eacii cap and bfnring frame 



Oil Grooves in caps and bearing 
B frame Si deep X g wide 




H 



¥"■ 



\I6 






Felt vyasher 



ci/»ss Industrial trade Machinist 

NAME John W.Roberts date Dec. 16-07. 



THE CARNEGIE TECHNICAL SCHOOLS 

pittsburgh, pa. 
School por Apprentices and Journeymen 
mechanical drawing 



Bench Grinder Frame 



SCALE p Size 



D^G NO. C- 1059 



LESSON Xo. 45, 



ASSEMBLY SPFXiriCATIOX. — On Drawings C-103S and 
C-1039 are shown the details of a Bench Grinder; from these details 
and the following information the student is expected to lay out a 
complete hah"-size assembly drawing of the Grinder. This drawing 
should be laid out upon a '■B'"-5ize sheet, showing the front and the 
end \"iews. 

The two emery wheels used are 8 inches in diameter by f inch 
thick, and have a f-inch bore. These wheels should be shown in 
place on the spindle, with an arrow indicating the direction in which 
thev revolve. 

The student must indicate which end of the spindle has a right- 
hand nut. and which end the left hand, thus showing whether he has 
clearly understood the reason for this practice. 

The whole assembly should be momited upon a cast-iron plate 



i'-8"Xi'-io"X|" thick. Use f-inch hexagon-head through bolts to 
fasten the bearing frame to the plate. 

Place the work-rest stands in front of the frame in the proper posi- 
tion to suit the wheel in each case. Use ^-inch square-head bolts \\-ith 
thumb nuts to clamp the stands to the plate. 

The student is expected to decide for himself the length of the bolts 
mentioned above, also the length of the cap screws for fastening the 
bearing caps to the frame. He must lay out a "Bill of Material" 
which will contain each item used in the construction of the grinder. 

Xo dimensions need be shown upon this assembly drawing, but it 
must be drawn accurately to scale. Make a tracing of the finished 
pencil drawing. 

The title of this drawing is "Bench Grinder Assembly," Drawing 
B-1040. 



LESSON No. 46. 



COMMUTATOR BAR.— The illustration shown on Drawino; 
C-1041 represents a Commutator Bar or a single segment of the com- 
mutator of an electric generator. 

The l)ar is cut from copper plate that has been rolled to the correct 
taper and thickness; the copper must he of the best quality and as 
hard as it is possible to make it, to insure good wearing qualities. 

These bars are cut to the dimensions shown by the .solid outline; 
they are then built up into a ring with strips of mica insulation be- 
tween the bars. This ring of !)ars is held by circular clamps while 
the inside of the commutator is bored out to the sizes indicated by the 
(lotted lines on the lower half of the bar. 

The necks are brazed into a slot milled in the toj) of the bar. 
The.se necks form a connection between the armature coils and the 
bars. 



The face of the bar is the part that helps to form the surface of the 
commutator which comes in contact with the carbons or brushes. 

The mica insulation shown is one of the best-known non-conduc- 
tors of electricity. Thin pieces of mica pasted together with shellac 
form the sheets from which these strips are cut or punched by means 
of dies. 

The term "P. D. Spec." refers to the "Purchasing Department 
Specification," under which many large firms purchase their supplies. 

The expression "Gauge Diameter" is one method used to denote 
the size of the commutator; it is of value mainly to the engineer and 
draftsman, as it is an imaginary diameter used as a basis when laying 
out the various parts of a commutator. 

Use a protractor when laying out the angular surfaces of the bar. 

Make this drawing carefully and accurately. 



' /s Taper per foof 



/aoer per foot 



Punch <5 Csk. for 



.IE8 Rivet {5) 




s 

St 



ar 






^0.^ 




/<nurl 
.-3696 Chord at Plofdia. 

£rvi;ca @ 



2745 Chord of L6fi dia. 



-J 



I 



i 
.0' 




■s 




■0 




t) 




-c 




■? ^ 


S 


C :; 




i^ ,^ 


3 



Bill or Material 



i 






Item 

No. 


Description and Material 


Pat No. 


i 1 

Peq. 1 Tool No. 





Comm.Bar copper /-3ff long.PD.SpecJ3l4 




192 'Gauge'26360 


@ 


Neck'.064IXl'x5£ Grade B copper strap 










PD. Specification 'l43l 




364 




® 


Rivets, S' 24558 




i584 




@ 


tvlica.£xsii'Xi~5fi' 




192 


Die' 22918 


@ 


Rivet , .188 Xg- copper wire 




192 





CLASS Industrial trade Machinist 
NAMC John W.Roberta date Jan. 12-09. 



THE CARNEGIE TECHNICAL SCHOOLS 

pittsburgh, pa. 
School of Apprentices ano Journeymen 
mechanical drawing 



Commutator Bar 



SCALE J Size 



owg.no. C.I 041 



LESSON No. 47. 



FRONT COMMUTATOR RING.— We mentioned in our last 
lesson that the commutator bars were held by circular clamps while 
beinsr bored out. After the boring is finished, the commutator mav be 
slipped onto the "spider," where it is held in place by V-shaped rings. 

On Drawing C-1042 is shown the front or outside ring. This 
ring is held in place by twelve f-inch studs screwed into the end of 
the armature spider. 

When laying out this ring drawing, use the "gauge line" as the 
starting-point, as this with the angular lines (3° and 30°) fix the posi- 
tion of the ring. 



The front ring is made of cast steel (c. s.) and should be machined 
all over. 

The narrow lip or flange on the outer edge of the ring is for the 
purpose of throwing off any oil that may leak out from the main- 
shaft bearings. If oil should work over the edge of the ring and get 
into the commutator, it is quite likely to "short circuit" and burn out 
the machine. 

These drawings are quite simple, but they must be drawn with 
care as to neatness and accuracy. 




CLASS Industrial trade: Machinist 
name: Jotin W.Roberts date: Jan. 16-09. 



THE CARNEGIE TECHNICAL SCHOOLS 

pittsburgh. pa. 
School of Appf/lmticcs and Journeymen 

mechanical drawing 



Front Commutator Ring 



SCALE 2 Size 



owg.no. C- 1 04 2 



LESSON No. 48. 



REAR C0:^OIUTAT0R RING. — On Drawing C-1043 is 
shown a Rear Commutator Ring. This cast-steel ring is to be shrunk 
t)nto a cast-iron armature spicier and, in connection witli the ring de- 
scribed in our previous lesson, holds the commutator bars tightly 
together in the form of a cylinder, the outer surface of which comes 
in contact with the carbons. 

For machines of low s])eed, these end rings are usually made of 
cast iron, the rear ring being a part of the armature spider, but it is 
much safer to use wrought iron or steel for machines of high speed, 
as the stresses are c^uite high through the nose of the ring. 



In addition to shrinking on, this ring is located in place by a 
f"X|"Xi5" key, shown on Drawing C-1044. 

A sectional view of the mica insulation rings is shown on our pres- 
ent lesson. One of these rings is placed at each end of the commu- 
tator bar, between the bar and the end rings, while the flat ring fits 
into the flanges of the end insulation rings, as shown, and over the 
body of the armature spider, insulating that from the commutator. 

As mentioned in the previous lesson, the student should make 
use of the "gauge line" as a starting-point when laying out this 
lesson. 



Finish these surfaces offer 
Shrinking on spider 




Sections of 

tvlica Insulation Rings. 
Moulds '££916 S 28917 



CLASS Industrial tkaoe Machinist 
NAME John Y/.Roberts date. Jan. 20-09. 



THE CARNEGIE TECHNICAL SCHOOLS 

PITTSBURGH, PA. 
SCHOOU OF APPRENTICE.S AND JOURNEYMEN 
MECHANICAL ORAVtINC 



Rear Comi^utator Ring 



SCALE ^ S Full Size owe. no.C-I 04 J 



LESSON No. 49. 



ARMATURE SPIDER.— The illustration on Drawing C-1044 
shows three views of an Armature Spider with the rear commutator 
ring keyed in place. The surface of this rear ring which forms the 
dovetail is finished after being shrunk on the spider. 

Some special sections are shown for the purpose of bringing out 
clearly the shape of the spider; in addition only half of the spider is 
shown, as this is sufficient and much time and labor are saved thereby. 

When building engine-type generators, it is often customary for 
one firm to build the engine and another firm to build the generator. 
The builders of the engine usually furnish the shaft, the sizes of which 
are indicated in the "stock order" furnished the generator builders. 



For the con^•enience of the student, he may show bores E, F, and 
G to scale for a diameter of 6 inches, and the keyway may be shown 
with W equal to i^ inches and H equal to ^ inch. 

The dovetail surface of the spider is turned to suit a "gauge" or 
templet made to suit this particular size and type of machine. 

\\Tien laying out this drawing, study for yourself the relation be- 
tween the spider and the parts detailed on the previous lessons, as 
this information will be of value in the following lesson. 

Lay this lesson out half-size on an A sheet (22"X3o"), as it is a 
poor plan to make a drawing to a small scale when it means a sacrifice 
of clearness to do so. 




Top for §s1ijd 

IB holes equa/ly spaced 



Section A- B \ Core for 6 shaft 

For H&Wsee 5.0. 



Sec f ion C-D 



For bores E.FSG see Stock Order 



CL^ss Indusfn'at trade Machinist 

NAuc John W.Roberfs date Jan.B6-09. 



THE CARNEGIE TECHNICAL SCHOOLS 

PITTSBURGH, RA\. 

School of Appif£:i\mcES aind Joui^seyuen 

MECHANICAL. DRAWING 



Armature: Spider 



SCALE ji. Size 



DiVG. 'vo. C_ I044- 



LESSON No. 50. 



COMMUTATOR ASSEMBLY.— On Drawings C-1041, C-1042, 
C-1043, and C-1044 are shown the main details of the commutator 
for an electric generator. From these drawings and the following 
information it is expected that the student will lay out an assembly 
drawing of the commutator. 

On this assembly drawing it is nesessary to show but one view — a 
lengthwise sectional view similar to Section C-D on Drawing C-1044. 

The main purpose of these later assembly drawings given in this 
course of lessons, aside from the general knowledge of the subject 
necessary in the drafting room, is to teach the student to think for 
himself. To lay out something which he cannot see requires him to 
think of and to clearly understand his problem before he can do the 
work. In other words, if the student is a mere copyist, he cannot do 
his work intelligently. 

Show one of the studs for holding the front ring in place with 



a ^-inch plain washer and a J-inch lock washer under the nut. 

Between the front ring and the nose of the spider which it fits over 
is an opening f inch wide and \ inch deep; this openiiig is filled with 
oakum packing to prevent dust and oil from working into the com- 
mutator from below. 

Where the mica insulation rings project beyond the ends of the 
commutator bar, they are wrapped with ^^g-'nch torpedo twine, and 
over that is wound a layer of surgical tape. 

Lay out this drawing to a half-size scale on a B-size sheet. 

It may be necessary for you to do some thinking before you can 
lay out this lesson, but that is what we expect you to do. 

When preparing the "Bill of Material," be careful to include each 
item required for a complete commutator. 

The title of this drawing to be "Commutator Assembly," Draw- 
ing B-I04S. 



LESSON No. 51. 



GENERATOR FRAME.— The main object of the lesson shown 
on Drawing C-1046 is to give the student additional practice, so that 
he may acquire the mechanical skill necessary to become a first-class 
draftsman. 

There is no relation between the generator frame drawing and the 
previous generator drawings, as this frame belongs to a machine of 
different size. 

\M:ere large castings are fitted together and the edges of the sur- 
faces which join are left rough, it is quite common practice to cast on 



what is known as a "chipping strip," or a narrow strip of metal that 
may be chipped and filed until the two edges of the castings match. 
These narrow strips of metal are more quickly and easily matched 
than wider surfaces would be. 

The "chipping strip" shown on the halves of the generator frame 
illustrates the value of the above-mentioned practice. 

Lay out this lesson on an A-size sheet, using a scale of one-quarter size. 

Do the best work you are capable of, as nothing but the very best 
you can do will be satisfactory. 




Item 
No. 


Description and t^ater'ial 


Pat No. 


Req. 





Hatf frame, C. 1. 


M. 7064 


2 


© 


tfE^s Bolt; W. 1. 




2 


® 


1x5' Ivf.B.Tap Bolt, W.I. 




12 


@ 


i'xSi' Stud Bolt with S.F: Nuts 




1 


© 


i'x4-Si ■• " - - - 




1 


® 


i'xTf'xB"Wasfier, WJ. 


2 



'/Drill and slot 
2gCbr,ideep 



/i Drill 



For pole details see Dwg.B-IO-4049 
For liners see Dwg. CI 1804-9 



CLASS Industrial traded t\/lact)inisf 
NAME. John W.Roberts date Feb. 6.09. 



THE CARNEGIE TECHNICAL SCHOOLS 

pittsburgh, pa. 
School of Apprentic£S and Journzvmcn 
mechanical drawing. 



Generator Frame 



SCALE 4 Size 



DtVG.No. C-/0-46 



LESSON No. 52. 



WORM GEARING.— The subject of the present lesson, Worm 
Gearing, is one with which shop men are not so familiar as they are 
with spur and bevel gearing, both of which are in more common use 
than the former for transmission purposes. 

For various purposes worm gearing is more desirable than bevel 
gearing, especially so where great speed reduction is necessary. 

The worm which drives the gear is simply a section of a screw, 
the thread of which is especially suitable for the purpose of engaging 
with the gear teeth. This screw thread is made with a flat top, the 
sides being inclined at an angle of 14° 30', or an included angle be- 
tween the sides of 29°, and is know as the Acme thread. 

To obtain the best results it is necessary to cut the teeth in the gear, 
by means of a "hob ' ' or tap, slightly larger than the worm. The pro- 
cess of " hopping a gear " consists of holding the hob and the gear in 
a suitable manner and revolving the hob against the edge or face of 
the gear until the teeth are cut to the correct depth. 

The ratio between the revolutions of the worm and the revolutions 
of the worm gear are as follows: 

Single thread worm = number of teeth in gear to i. 
Double " " = " " " "■ " " 2. 

Triole " " := " " " " " " 1 

Quadruple " " = " " " " " " 4. 

By the term " pitch " of worm is meant the linear distance a nut 
travels for each revolution of the screw. 

The increased speed of the gear driven by a double-thread worm 
(compared to a single-thread worm) is not due to the worm being 
double threaded, but is due to the increased pitch of the worm, which 
makes a double thread a mechanical necessity, as in double-thread 
screws a single thread of the same pitch would weaken the worm too 
much, often nearly cutting it in two. The double-threaded worm 
presents more tooih surface in contact at the same time, thus adding 
materially to the strength and wearing qualities of the worm. 

To get good results with high-speed worm gearing, the worm 
should be made with the outside diameter about equal to the pitch; 



this gives a tangent thread angle of 17° 15'. Several authorities prefer 
a worm with even greater pitch, so as to give a thread angle of 20°. 

The circular pitch of the worm gear is equal to the linear distance 
from the center of one tooth to the center of the next tooth of the 
worm. 

USEFUL WORM-GEAR FORMULAS. 



Circular pitch or C. P.: 



D. R 



(71=3.1416). 



Diametral pitch or D. P. = 
Pitch diameter 



C. P.- 

Number of teeth X CP. 



Throat diameter = pitch diameter- 
Blank diameter = pitch diameter 



D. P. 



D. P. 

Teeth of gear are of the same proportions as a section of the worm 
thread. 

Addendum or height of tooth from pitch lines to throat=z 



D.P.- 

Dedendum or tooth below pitch line=addendum-|-clearance. 

Clearance=one-eighth of addendum height. 

Whole depth of tooth = addendum -j- dedendum or C. P. X.6763 

Width of worm thread at top = C. P. X. 33 54. 

Width of thread tool at end=:C. P. X. 3148. 

The face of the worm gear is usually made equal to from one-half 
to three-fourths of the outside diameter of the worm. 

LESSON. — On Drawing C-1047 is shown a worm gear of 48 
teeth, 3-inch pitch quadruple, engaged with a worm of 3-inch pitch 
quadruple thread. From the formulas given above the student is 
expected to obtain all the dimensions necessary to lay out this gear 
and worm. Put in the correct dimensions where they are shown 
blank on this drawing. 

Make your tracing neatly and carefully. 




CLASS Industrial trade. Machinist 
NAME John W Roberts date Jan. 6.09. 



THE CARNEGIE TECHNICAL SCHOOLS 

frrrsBufxSH, pa. 
School, of Appkentices and Jou^nEvMEf/ 

MECMANICAL. DRAWING 



WoRf<^ Gearing 



SCALE 3 Size 



OYtG.No. C.I 047 



LESSON No. 53, 



PLATE CAM. — The subject of cams is such a large one that we 
can touch upon it but briefly in this course of lessons. 

Cams may be divided into two classes: "positive" and "non-posi- 
tive." Each of these classes may be again subdivided into many 
types of cams. 

A positive cam is one where the impulse transmitted by it is definite 
and continuous, as the motion transmitted by gear wheels. A non- 
positive cam lifts a roller or slide by the friction of its surface, but the 
roller or slide falls back to rest of its own weight, or is pulled back by 
a spring. 

Our present lesson is an illustration of a non-positive cam. This 
is one of the many cams the body of which is an irregularly shaped 
plate mounted upon a shaft; the edge of the plate, revolving against a 
roller or slide, lifts or pushes it in a plane at right angles to the 
shaft. 

The problem is to lay out a cam that will raise the lever roller 
from rest on the base circle ik inches during one-si.xth of a revolution 
or 60°, the lever to remain stationary for 60° of the revolution, to 
fall f inch in 30° to remain stationary for 45° to fall the remaining 
f inch to rest in 30°, and to remain at rest for the balance of the 
revolution. 

In practice the size of the shaft and the hulj diameter of the cam 
fix the minimum diameter of the base circle, for this should be at 
least J to J inch larger in diameter than the hub. 

When the size of the base circle has been decided, lay out the 
motion diagram or chart, which is a graphical picture of the path of 
the cam roller. The length of the base line of the chart is equal to 
the circumference of the base circle. Each of the spaces between the 
vertical lines represents 15° on the present chart, but the base line 



may be divided into any number of equal divisions that will suit the 
degrees of circumference occupied by the various movements. 

This chart should be laid out to scale as to length, proportionate 
divisions of length, and the height or throw. Full size is preferable 
where possible. 

To get the best results as to wear, the edge of the cam or the 
curved path of the roller should be so designed as to create the least 
friction possible. What is known as the harmonic curve is used 
largely by designers of cams. This curve is illustrated on our present 
lesson and is laid out in the following manner: 

Throw in a semicircle equal to the "throw" of the cam; divide 
this half circle into an equal number of parts — the same number into 
which tlie angle of the movement is divided. Project these division 
points upon the base line of the semicircle, then with the compass 
pivoted at the shaft center, swing in circular projection lines from 
these base-line points until they intersect the radial division lines. 
The points of intersection are the points forming the desired curve, or 
if allowance was made for the radius of the roller, as in our present 
lesson, these points are the center of the roller in the different posi- 
tions it would take in moving around the cam. 

In actual practice the cam revolves against the roller, but for the 
convenience of the draftsman, the work is laid out as if the roller were 
moved around the cam. 

For the benefit of those students who have not understood the 
meaning of the term "throw" in this lesson, it should be explained 
that this refers to the distance the roller moves away or toward the 
shaft center as the cam revolves. 

Make a full-size pencil drawing and tracing of the plate cam illus- 
trated. 




CLASS Industrial TRADE Mach'in'isf 

NAME John V^. Roberts date: Jan.l2-09. 



THE CARNEGIE TECHNICAL SCHOOLS 

PITTSBURGH, PA. 

School or Apppestices ano Journeymen 

MECHANICAL DPAWING 



Plate Cam 



SCALE Full size 



Dwa. No. C_ I04-8 



LESSON No. 54. 



PERIPHERY CAM.— The Periphery or Cylindrical Cam illus- 
trated in our present lesson is one of the many types of positive cams in 
general use. This cam operates a lever with a " throw " or radial move- 
ment of i^ inches. The small circles shown in the development of the 
groove represent the roller in different positions during the movement. 

The formulas given are based upon an angle of 30° which is tan- 
gent to the middle point of the center line of the cam groove, as shown 
in the illustration. The value of n in the formulas equals the number 
of degrees of the circumference occupied by the movement. 

It has been found that 30° is the maximum angle we can use to 
obtain the best results, and from the above-mentioned formulas we 
can get the minimum cam diameter, using this angle. 

The purpose of the chart is to show a graphical picture of the cam 
movement; thus it will serve as a general layout for the movements 
of all the cams on a machine. 

For most movements straight lines from point to point will answer 
on a chart, and as they are more easily and quickly drawn than the 



true lines, much time may be saved by their use, but the student should 
realize that the actual path of the roller is a curved line, as illustrated 
by the cam-groove development, and for special cases it is necessary 
to plot these movements carefully. 

Lay out a full-size pencil drawing (on a B-size sheet) of a periphery 
cam with a throw of i^ inches, forward movement of the lever roller 
to take place in one-sixth of a revolution or 60°, to pause at the end 
of the stroke 35°, and to return to rest in 60°, the lever to remain at 
rest for the balance of the revolution. The lever arm is 10 inches 
long to the fulcrum. 

The distance B can be calculated from the chart, the length of 
which equals the cam circumference. Each vertical line represents 5°, 
and each horizontal line equals \ inch. 

Do this work very carefully and accurately, making a tracing of 
the finished pencil drawing. 

The formulas given are taken from "Design and Construction of 
Cams," by Smith and Halsey. 



A=ThrowX2.72 



.^9.7PX Throw X 360 




Throw 



-0 

























































Com Circumference in Degrees 

/40 150 160 170 ISO 190 200 210 220 2^0 24-0 250 














































10 20 JO AQ 50 6 


70 80 90 100 110 ISO 130 


260 270 2Q0 2903003)0 320 330 340 350 3i 


so 




























































































































































































































































































































































































































































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CMSS Indusirial trade Machinist 
NAME John W. Roberts date Feb. 10-09. 



THE CARNEG/E TECHNICAL SCHOOLS 

pittsburgh. pa. 

School of apprentices and Journeymen 

mechanical drawing 



Periphery Cai^ 



SCALE ^ Size 



DwG./vo. C-1049 



LESSON No. 55 



STRUCTURAL DRAWING.— A general knowledge of the prac- 
tice in structural drafting rooms is of value to the mechanical drafts- 
man, even though he stick to machine work for a livelihood, as there 
are frequently times when it is necessary to do some special work 
pertaining to building construction. 

The following lessons were planned for the purpose of familiar- 
izing the student with general practice as to the conventional signs 
and methods in use in most structural drafting rooms. 

Make a neat pencil drawing and tracing of the subjects shown on 
Drawing C-1050. 

These signs for riveting are in general use by manufacturers of 
structural steel. The rivet proportions given are for the use of the 



draftsman only, and are intended for his convenience when indicating 
rivets on drawings of structural shapes. 

"Shop Rivets" is the term used in designating rivets that are to 
be driven in the shop. 

"Field Rivets" is the name given to rivets left to be driven during 
the erection of the structure. 

In reference to the terms "inside" and "outside": by the term 
"inside" is meant the side of the work that is behind or invisible, and 
the term "outside" refers to the side that can be seen on the drawing. 

In making this drawing the student is at liberty to use any size 
rivets or plate thickness he may desire, though J-inch rivets and ^-inch 
plates were used in the illustration. 



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CL/tss Industrial trade Machinist 
NAME John W.Roberfs datc Feb. 16-09. 



THE CARNEGIE TECHNICAL SCHOOLS 

PITTSBURGH, PA . 
SCI-iOOL or APPREhfTICElS AND JOURNCYMEH 
MECHANICAL. DRAWING 



Rivet Proportions 
Conventional Signs 

.€ OWG.Iso. C-'05Q 



LESSON No. 56. 



RIVETED JOINTS.— The riveted joints most used in structural 
work are "lap joints" where the plates overlap, and "butt joints" 
where the ends of the plates butt together, with other plates placed 
over the seam on each side. 

The terms "single riveted," "double riveted," and "chain riveted " 
are clearly indicated on Drawing C-1051, and should need no ex- 
planation. 

The distance from center to center of rivets is called the "pitch." 
In the present lesson the pitch is 3 inches. 

While rules often varj' with different firms, it is generally considered 



good practice, when locating rivets in relation to the sides and ends of 
the plates, to use the rules shown on the illustration. 

Three-fourth-inch rivets are used in this lesson; the sizes of the 
heads can be obtained from Lesson No. 55. 

The student should notice that the method of indicating the scale 
of the drawing differs from that used on drawings of machinery. He 
can readily understand why drawings of machinery are proportioned 
to the inch, while those of buildings, bridges, etc., should be per 
foot. 

Make a neat pencil drawing and tracing of this lesson. 



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CLASS Industrial trade Machinist 
NAME John W.Roberts date: Feb. 18-09.. 



THE CARNEGIE TECHNICAL SCHOOLS 

piTTsaufiaH, PA. 
School, or Apprentices and Journeymen 

MECHANICAL- DRAWING 



Riveted Joints 



SCALE 3=1-0 



one. NO. C_I05I 



LESSON No. S7' 



STANDARD FRAMING.— Make a neat pencil drawing and 
tracing of the examples of Standard Framing shown on Drawing 
C-1052. 

Most of the dimensions have been left off of the illustration, as it 
is not customary to show dimensions of I beams, but to give the depth 
and length with dimensions for rivet holes. 

All necessary information to make this drawing, such as size of 
angles, positions of rivets, and dimensions of I beams, may be ob- 
tained from the handbook of the Carnegie Steel Company. 



"L's" is the term commonly used to indicate "angles," as sections 
of angle iron are called. Thus "2 L's 4"X4"Xt^"Xi' 6", wt. 43 
lbs.," describes briefly a pair of angles the legs of which are 4 inches, 
the thickness -/g- inch, the length i foot 6 inches, and the weight 
43 l^s. 

Three-fourth-inch rivets are used; the size of head and the con- 
ventional sign for field rivets can be obtained from Lesson No. 55. 

Make this drawing to the scale given, and put in the dimensions 
relating to the rivets, as shown by the dimension lines. 





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Ci/\ss Industrial trade Machinist 

hJAMC John W. Roberts date Feb. 2A_ 09. 



THE CARNEGIE TECHNICAL SCHOOLS 

pittsburgh. pa. 
School of Apprentices and Joupnevmen 
mechanical. drawing 



Standard Framing 



SCALE J'= 1-0 



DWG.no. C_ loss 



LESSON No. 58. 



BEAM CONNECTIONS. — Two connections which are quite 
generally used to fasten large I beams to columns are shown on 
Drawing C-1053. 

The connections for smaller beams are usuall_v much simpler than 
those shown, so that the student should have no trouble to understand 
them should it be necessary for him to do some structural work. 

The student should observe the method used to designate the 
various details, such as "L's" for angles, "PI." for plate, "Guss." for 
gusset plate, and "Fill." for filler plate. 



A great deal of time and labor are sa\^ed ])y the method illustrated 
of indicating the dimensions of a detail, and the drawings are less 
complicated than they would be if each detail were dimensioned, as 
is necessary on drawings of machinery. 

A careful study of these details will help the student to a clearer 
understanding of the methods followed in building up beam connections. 

Notice also the method shown for dimensioning rivet spacing; 
this saves repeating a small dimension several times. 

Make a pencil drawing and tracing of this lesson. 



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CLASS Industrial trade Machinist 
NAME John W.Roberts oatc reb. 96.09. 



THE CARNEGIE TECHNICAL SCHOOLS 

pirrsBuRGM, PA, 
School roff Apprentices and journeymen 

MECHANICAL DRAWING 



Beam Connections 



SCALE lj=l-0 



Dwe.Nc. C-1055 



APR 14 1909 



LIBRARY OF CONGRESS 




019 945 461 4 







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